The Technology of Construction

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The Technology of Construction


New Building Technologies. Two of the most enduring images of the Middle Ages are castles and cathedrals. To construct these magnificent structures medieval building technology advanced to limits the Romans had never approached and used available materials in ways they had never imagined. Medieval builders constructed castles and cathedrals largely from cut stone and used quicklime mortar—sometimes to hold the blocks in place, but more often to fill in gaps. Their solid blocks of stone had to fit together with tolerances of less than a quarter inch (5mm). Though they could use water-powered mills for cutting stone from the quarries into uniform slabs, most of the work was still done by hand with hammer and chisel. By the thirteenth or fourteenth century, the magnificent castles and cathedrals of medieval Europe had begun to revive the “lost glory” of ancient Rome.

Cathedrals. While they were built to exemplify the glory of God, the cathedrals of Europe also stand as monuments to the ingenuity of architects and stonemasons who made them. The adoption of Christianity in the later Roman Empire and its eventual spread throughout Europe provided the motivation for raising big cathedrals and churches. Cathedral building was also intimately tied to the increasing power of cities and the growing influence and wealth of town dwellers, particularly in the twelfth and thirteenth centuries. Europeans inherited an understanding of monumental building from the Romans, but the undertaking of such projects was unusual until the medieval period. In trying to re-create the glory of Rome in the Holy Roman Empire, Charlemagne built an ornate Romanesque palace at Aachen, in eastern Germany, during the eighth century, but it was a lone example.

Romanesque Architecture. Especially in its monasteries, the Church re-created the power and economic force of the Roman Empire. By the ninth and tenth centuries the largely self-sufficient monasteries had become centers of cultural expression. Beyond the society they molded, the art they created, and the literature they preserved and augmented, the building of churches became the centerpiece of their existence. Because they were inspired by the Roman ruins around them and built in conscious imitation of Rome, the solid churches built throughout Europe from the seventh through the twelfth century are known as Romanesque buildings. Their characteristic features are thick walls, small windows, and semicircular arches throughout the building. Although the main central spaces, or naves, reach stunning lengths and heights in some Romanesque churches, they are darker and more somber spaces than the Gothic-style churches that succeeded them.

Barrel Vaults. In Romanesque construction the large open space of the nave was either covered with a flat wooden ceiling supported by large transverse wooden beams, or it was spanned by a stone barrel vault. Used in large-scale Roman buildings, the barrel vault is essentially a round arch extended along the length of the nave. While it covers the nave in a majestic fashion, as the nave to be spanned grows wider, an increasingly thicker vault must be built. As barrel vaults grew thicker and thicker, they also became heavier and heavier, so the walls on which a vault rested had to be made thicker, not only to carry the weight of all that stone but also to resist the tendency of an arched structure to push outward at its base. In architectural terminology this tendency is known as thrust. Initially, Romanesque churches dealt with thrust by building thick, windowless walls, but over time, a desire for some natural light drove builders to put intermittent reinforcing pillars along the outside of the walls.

These pillars, called buttresses, took the load of the vault, while the walls between them could be made slightly thinner and pierced safely for windows. The development of buttresses predicated the Gothic form.

Cluny. The culmination of the Romanesque style was the monastery of Cluny, in Burgundy. Founded in 909 by Benedictine monks, Cluny became the greatest monastery of their order, and it was considered one of the greatest monastic building complexes in Europe until its destruction in 1790 during the French Revolution. A succession of three churches graced the monastery, and the third, built between 1089 and 1132, was the largest church in Christendom until the sixteenth century. A massive Romanesque construction, with a central nave 99 feet (30m) tall and 555 feet (169m) long, the church stood as the centerpiece of a 25-acre (10.1 ha) monastic complex.

Gothic Architecture. By the end of the twelfth century, as the Romanesque style was reaching its height, changes in church construction inaugurated a new style, later disparagingly called “Gothic” during the Renaissance, when it was called barbaric in comparison to the Roman models that influenced the architecture of that period. Today, however, the Gothic style is seen as the pinnacle of medieval architecture. Gothic cathedrals are highly ornate structures. Their sculpture became increasingly naturalistic and expressive. As these impressive churches soared higher and higher, the manner in which they were constructed made them much stronger for their size than Romanesque churches, allowing their stone walls to be interrupted with large expanses of stained glass instead of the small windows that made the interiors of Romanesque structures so dark.

Groin Vaults. Gothic cathedrals were able to achieve great heights through innovations in constructing their vaults and the columns that support them. Architects learned that if they built two intersecting barrel vaults, one running the length of the nave and the other running its width, they could overcome many of the limitations of the single barrel vault. The resulting creased ceiling was called a groin vault. Though this vault can be created with two of the same semicircular arches used in Romanesque architecture, early in the twelfth century European architects discovered that using pointed arches made it possible to make a higher ceiling, and this pointed form made the structure even more rigid. Any structure with creases is more stable than one without them, and can therefore be made thinner. Thus, the pointed Gothic vault used considerably less stone than its Romanesque predecessor. A groin vault generates considerably less thrust than the barrel vault, and a pointed groin vault even less than one with semicircular arches, so a Gothic ceiling could be set atop thinner walls than a Romanesque ceiling of the same size. With arches spanning the length and the width of the nave, the walls no longer needed to be continuous and could be reduced to a series of columns, or piers. The space between them could then be filled with stained-glass windows.

Rib Vaulting. Further refinements were made throughout the Middle Ages. Early Gothic groin vaulting gave way to rib vaulting as early as about 1180, in which the lines of intersection of the vaults were constructed first by creating an arch, or rib, between diagonally opposed piers. With the ribs in place, stone webbing—the minimally structured membranes that fill the space between the ribs—could easily be laid between them to complete the vault. This development allowed the webs to become even thinner, further reducing the weight of the vault and allowing it to be built higher and higher above the church floor. This innovation made possible the construction of soaring cathedrals, but it created new problems for the builders to solve.

Flying Buttresses. Medieval cathedrals with tall, pointed vaults projected high above the landscape, where winds were much stronger than at ground level. Even if the vaults and the roofs did not generate too much thrust, the pressure of the wind hitting the roof broadside did. The solution was to increase the buttressing. Buttresses constructed to support high roofs rose above the tops of the side aisles and became free-standing arcs of stone. These new “flying buttresses” received the thrust of the roof and vault and transferred it to the ground. As time passed, flying buttresses were adorned with elaborate detailing and their own ornate spires. Not only did they complement the artistry of the church, but these pinnacles also added extra weight on the buttresses to provide increased stability in high winds.

Builder’s Tools. To create these majestic cathedrals, builders had the straightedge and compass to set out the plan, the simple hammer and chisel to carve stone blocks, and human- or animal-powered tread-wheel hoists to lift the blocks in place. Medieval builders excelled at the geometric construction of cathedrals. There are no known blueprints for complete cathedrals. Instead, scholars have, in a few instances, found templates for the fundamental geometrical constructions that underlie the size, shape, and proportions of a church. Everything, from the overall length and width of the church, down to the curve of the arches and the window mullions, is related through simple geometry to some modulus, or base unit. In a few churches the modulus and base curves for the entire church are inscribed on the floor of the nave. Builders might work out the basic idea on paper, but then they laid out full-scale templates on the building site. Masons would cut stone to fit and work it to a finished or near-finished condition. These blocks would then be hoisted aloft, fitted in place, and possibly given a final fine dressing. Overall, in structures tens of meters tall and hundreds of meters long, medieval architects and builders managed accuracy on the order of centimeters or even of parts of centimeters in many cases.

Rapid Development. Between the mid twelfth and the mid thirteenth centuries medieval architecture advanced through these stages so rapidly that cathedrals begun a mere fifty years apart were vastly different in scale and feeling. The nave of Laon cathedral, begun in 1175 and exhibiting all the elements of Gothic architecture, reached a stunning height of 80 feet (24m). Rheims cathedral, begun a mere fifty years later in 1225 and exhibiting mature Gothic elements such as flying buttresses and steeply pointed arches, soared to 125 feet (38m). These buildings and other Gothic cathedrals were stunning places of worship, with painted interiors and vast panels of stained glass. In Christian theology the Holy Spirit is personified in light and light beams, and these soaring houses of worship glorified not only God but their builders as well.

Castles. Castles were raised to the glory of man. In a Europe still far from unified, castle building was stimulated by hostile or potentially hostile relations among neighboring lords. Castles and fortified cities became a common feature throughout Europe, not only in areas such as Germany and Italy, where competing princes and dukes fought for political control, but even in countries that became unified at an early date—notably France and England, where the landscape was dotted with castles that rulers used to maintain their power. In Italy, the Tuscan town of San Gimignano had dozens of fortified tower houses, each built by a different family or faction, not only for protection from invaders, but also from each other. In Germany castles were built along the Rhine River to control and tax river traffic. In some cases, as in Wales under Edward I, castles served to bring or keep a local population under control and to cow local lords into obeisance to a regional lord or king. Fortification allows an individual to establish and maintain power. While it provides security for the

inhabitants of a region by providing a refuge in times of crisis, it is also a reminder to them of the certain power of the local lord and the potential power of the ruler of the state. Although the common image of medieval battle is one of chivalrous knights jousting and fighting in full armor, in reality most medieval warfare was conducted through sieges. Because surrounding and attacking a castle or a fortified city occurred much more frequently than infantry battles, good fortifications were much more important than knights. Consequently, fortification technology was remarkably dynamic throughout the Middle Ages.

Early Castles. Fortifications went through several distinct phases from the fall of Rome in the fifth century to the advent of effective gunpowder artillery in the sixteenth. At first, fortifications were simply stout wooden buildings. If they could be built in places that were naturally protected, such as high hills or ocean cliffs, so much the better, but more often than not they were placed where they were most needed, near centers of population. Therefore, castle builders had to make their own defenses, usually by making hills and building castles atop them. The hill—whether natural or artificially constructed—was called a motte (the French word for mound or hill). Around the base of the motte, the lord would build housing for his servants and household, creating a village that would attract people such as craftsmen, soldiers, cooks, brewers, and leather workers to settle there as well. Since it was in the lord’s interest to protect these people too, a “palisade,” or fence of tall pointed stakes, was built around the motte and these outbuildings. The area between the palisade and the motte was known as the “bailey,” so the general term for these early fortifications is motte-and-bailey castle. Motte-and-bailey castles were first built in France, although their precursors, prehistoric hillforts, exist all across Europe. Motte-and-bailey castles spread to England and in a sort of modified form around western Europe.

Castle Walls. As the power of rulers grew, they took many craftsmen and support staff into their households. The wooden palisades were replaced with stone and the separation of motte and bailey shrank. By the thirteenth century, castles were built with a large stone tower, or keep, and an encircling stone wall. This wall enclosed smaller buildings—usually built along its inside—to house the trades originally located in the bailey.

Building for Defense. Castle building for the purpose of defense developed substantially from the eleventh century to the fifteenth century. The simple wall with a gate developed into a set of interlocking defenses designed to keep attackers out for as long as possible. Moats were dug around the outer walls, and were either kept full of water or else built in such a way that they could be flooded in time of crisis. The drawbridges that spanned the moats were retractable to prevent unwanted entry. Huge iron and wood grates called portcullises were placed just behind the drawbridge

as well as at the far end of the gatehouse, so that if attackers crossed the moat and gained entry, they could be caged between the portcullises, where defenders could attack them from above and through narrow slits in the walls at the sides. These narrow vertical slits (sometimes also augmented by a short horizontal one to make the hole cross shaped) were only a few inches wide on the outside, but were a few feet wide on the defenders’ side of the wall. These funnel-shaped openings, known as arrow loops, allowed defenders to shoot arrows through the wall with about a 75–90 degree arc, while presenting a tiny opening for enemy archers. Later, circular holes were carved at the bottom of each arrow loop to accommodate small cannons and handguns. The tops of castle walls were crowned with ramparts, which had regular gaps—called crenellations—for firing arrows—or later guns—at attackers. Some castles were built with multiple sets of walls, so that even if attackers breeched the main wall, they then had to attack another set of walls while vulnerable to defensive fire.

Eastern Influences. There is a great debate among historians over what role Europeans’ experiences in the Crusades played in the development of castles. Earlier historians thought that the Crusaders learned many of the building and defensive methods they applied at home directly from Muslim castles, particularly in Syria. More-recent historians have suggested that the Europeans were developing many of these techniques on their own and that the Crusaders’ observations in the Holy Land were a catalyst to use these building methods more widely. Still later historians have suggested that the exchange was mutual: Syrians and Europeans learned from each other. In any case, after the Crusaders returned from the Near East during the twelfth and thirteenth centuries, increasingly large and complex stone castles were built all across Europe.

Castle Architecture. Medieval castle builders took a different approach to construction from cathedral builders. Cathedrals soared ever higher as their walls became thinner and delicate, but as castles grew larger and larger, their walls became more and more massive. Churches were usually built anew, completely replacing older religious buildings; castles evolved and were expanded over time, absorbing, modifying, and extending defensive structures already in place. The architectural challenges of castles were never as formidable, nor as creatively solved, as those of cathedrals, but throughout the Middle Ages castle building, like cathedral building, was an important opportunity for builders to display their skills through expansive, and expensive, use of stone, labor, and energy.

Castles as Country Houses. By the end of the Middle Ages the castle had begun to lose its military function. One reason was the rise of gunpowder weaponry, which changed how wars were fought. Another was the growth of state power, especially in England and France. Strong castles in the countryside posed a threat to centralized monarchies, so powerful kings discouraged castle destruction and sometimes even destroyed them. As a ruler consolidated his hold over his kingdom, the strategic military importance of castles decreased. Instead, they became mostly centers of provincial administration for lords, both as landholders and as agents of the crown. Castles multiplied to the point that a given lord might make an annual circuit of his castles, and they functioned more like the country houses they became after the Renaissance.

Furnishing Castles and Cathedrals. Once completed, castles and cathedrals needed furnishings and decorations. In the course of fulfilling the demand for such niceties, medieval artists achieved new heights of creative power, and technological innovation kept pace. Contrary to popular opinion, the mechanical processes of artistic creativity involved in decoration of cathedrals and castles were not the sole responsibility of uneducated townsmen. In 1122 the German monk Theophilus Presbyter wrote On Divers Arts, in which he explained the creation of artists’ pigments and gold amalgams and the art of metal casting. The book is essentially a textbook of medieval artistic craft skills, and as such it is of extraordinary value to historians. Theophilus was a monk, educated in and dedicated to theological learning, but his knowledge of complex techniques and his refined tastes suggest that he was also a goldsmith and painter. Traditionally, the professions of monk and artisan did not go together, but Theophilus provides evidence that in the early twelfth century, this division of labor was breaking down. Slightly later, Hugh of St. Victor, in Paris, wrote his Didascalicon (circa 1125–1130), in which he defended the “mechanical arts”—everything from brewing to leatherwork, metal-working, and military technology—as not only useful, but also desirable and honorable. He also provided the first European account of the bell, at just the time that bells were becoming common in the churches that were being built at a prodigious rate throughout Europe.


Jean Gimpel, The Cathedral Builders, translated by Carl F. Barnes (New York: Grove, 1961); translated again by Teresa Waugh (New York: Grove, 1983).

Theophilus Presbyter, On Divers Arts: The Treatise of Theophilus, translated by John G. Hawthorne and Cyril Stanley Smith (Chicago: University of Chicago, 1963); also translated by C. R. Dodwell as The Various Arts (London: Nelson, 1961).

Wolfgang F. Schuerl, Medieval Castles and Cities, translated by Francisca Garvie (London: Cassell, 1978).

Elizabeth Bradford Smith, and Michael Wolfe, eds. Technology and Resource Use in Medieval Europe: Cathedrals, Mills, and Mines (Alder-shot, U.K. &Brookfield, Vt.: Ashgate, 1997).

Sidney Toy, Castles: A Short History from 1600 B.C. to A.D. 1600 (London & Toronto: Macmillan, 1939).

Lynn Townsend White Jr., Medieval Religion and Technology: Collected Essays (Berkeley: University of California Press, 1978).