An elaborate loculus, or catacomb grave. The word may owe its origin to arcus (arch) or arca (coffin) and solium (throne). The processional litter used in antiquity in the burial rites of important personages was called a solium. By extension, the tomb itself came to be called a solium, and the term was used in this sense by certain ancient writers (Curtius, Hist. 10.10; Suetonius, Nero. 50). The arcosolium was formed by excavating in the wall a space similar to that of an ordinary loculus and surmounting the space by an arch. The arch facilitated the opening of the downward cavity where the corpse was to be laid. Arcosolia differed from loculi in elegance and in the mode of closing. Loculi were closed vertically by a marble slab fixed to the wall, whereas arcosolia were closed horizontally. Above the horizontal slab was an arch or vault of stucco, frequently ornamented with frescoes. A more ancient form of arcosolium was the arched niche excavated to floor level; sarcophagi were placed in this earlier type. Although some arcosolia are found along the passages of the catacombs, the greater number are located in the cubicula. Arcosolia were used everywhere in Rome during the 3d century, and many later martyrs were interred in them.
Bibliography: Centre de Pastorale Liturgique, Le Mystère de la mort et sa célébration (Le Orandi 12; Paris 1956). h. leclercq, Dictionnaire d'archéologie chrétienne et de liturgie 1.2:2774–87. o. marucchi, Le Catacombe romane (Rome 1932) 312–336. j. kollwitz, Reallexikon für Antike und Christentum 1: 643–645; 3:231–235. p. testini, Archeologia cristiana (Rome 1958) 75–326. f. de visscher, Analecta Bollandiana 69 (1951) 39–54.
[m. c. hilferty]