Tetraconch

A tetraconch, from the Greek for "four shells", is a building, usually a church or other religious building, with four apses, one in each direction, usually of equal size. The basic ground plan of the building is therefore a Greek cross. They are most common in Byzantine, and related schools such as Armenian and Georgian architecture. It has been argued that they were developed in these areas or Syria, and the issue is a matter of contention between the two nations in the Caucasus.^[1] Apart from churches, the form is suitable for a mausoleum or baptistery. Normally, there will be a higher central dome over the central space.

Overview

The Basilica of San Lorenzo is possibly the first example of a grander type, the "aisled tetraconch", with an outer ambulatory. In middle Byzantine architecture, the cross-in-square plan was developed, essentially filling out the tetraconch to form a square-ish exterior. Either of these types may also be described less precisely as "cross-domed". In these types the semi-dome of the apse usually starts directly from the central domed space.

The

Jvari monastery, see plan above). Later a different plan was developed, with a tetraconch main space completely encircled by an aisle, or ambulatory in the terminology used for Western churches,^[2] as at the ruined mid-7th century Zvartnots Cathedral.^[3] The ruined so-called Cathedral of Bosra, of the early 6th century, is the earliest major Syrian tetraconch church,^[4]

though in Syria the type did not remain as popular as in the Caucasus.

The Mausoleum of Galla Placidia in Ravenna (425–30), world-famous for its mosaics, is almost a tetraconch, although there are short vaulted arms leading from the central space to each apse-end. These end in a flat wall with no semi-dome, and the entrance end is slightly longer.

A famous revival of the tetraconch formula in the West is

Basilica of St. Peter

, Rome.

Plan of Saint Hripsime Church, Armenia, 4-7th century
St Peter's Basilica
, 1503–06
Floorplan of Saint Sava, Belgrade, 2004

Triconch

Sankt Maria im Kapitol, Cologne

A triconch building has only three apses; normally omitting the one at the liturgical west end, which may be replaced with a

St. Mary of the Mongols is an example. Many triconch churches were built with a nave from the start; this formula was very common in the West, especially in Romanesque architecture

.