A tetraconch is a square or oblong room expanded on all four sides by semicircular rooms formed by a portico or open recess (conchas, or exedrae). The origin of the tetraconch is a matter of debate. Numerous examples suggest Syria or Asia Minor, but the Church of San Lorenzo is a fourth-century example from Milan. It is not native to Egypt, although there are a few tetraconch churches there, for example, at Abu Mina.
The tetraconch provides a church building with a particularly rich interior structure. The inner rectangular room has numerous columns and usually a wooden roof. The exedrae are formed by the erection of columns. The eastern one serves as an apse. The external shape of the church varies.
Most frequently it has a wall of concentric design, shaped so that an ambulatory is created between it and the internal columns, as in the East Church at Abu Mina. Areas of the external wall may be utilized to accommodate the side rooms required by the liturgy. The Martyr Church (Justinian phase) at Abu Mina, however, has a rectangular external wall.
- Balty, J. C. “Le Groupe épiscopal dApameé, dit Cathédrale de lest.” In Colloque Apamée de Syrie. Brussels, 1972.
- Grossmann, P. “Die zweischaligen spätantiken Vierkonchenbauten in Ägypten und ihre Beziehung zu den gleichartigen Bauten in Europa und Kleinasien.” In Das römisch-byzantinische Ägypten. Aegyptiaca Treverensia 2. Mainz, 1983.
- Kleinbauer, W. E. “Zvart‘nots and the Origins of Christian Architecture.” Art Bulletin 54 (1972):245ff.