atrium

atrium (pl. atria).
1. Small court or principal room in a Roman house, called cavaedium or cavum aedium, usually surrounded by a roofed area, supported on columns, disposed with the compluvium or roofless opening in the centre. Rainwater was channelled into an impluvium, cistern, pool, or tank set under the opening in the floor. Types of domestic atrium include:atrium Corinthium: with more than four columns (i.e. a peristyle) supporting the edge of the compluvium;atrium displuvatium: with the roof sloping away from the compluvium, the rain being carried away by means of gutters and pipes;atrium testudinatum: with no compluvium, but crowned with an arched vault (testudo);atrium tetrastylum: with four columns, one at each corner supporting the compluvium;atrium Tuscanicum: insignificant and astylar with the roof carried on two beams with two short beams or trimmers.

2. Open court surrounded by a roofed arcaded or colonnaded walk, laid out before the west end of an Early Christian, Byzantine or medieval church, sometimes planted with trees, and often with a fountain in the centre. An interesting survival is the atrium of Sant'Ambrogio, Milan (c.1140). In this sense, the atrium was the forerunner of the cloister.

3. Top-lit volume surrounded by several storeys, e.g. Portman's Hyatt Regency Hotel, Atlanta, GA (1967–71).

Bibliography

Blaser (1985);
D. S. Robertson (1945);
Saxon (1994)