The
Basilica of San Lorenzo, Milan (370) 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. , one of the first Tetraconch churches in the world The ruined
Ninotsminda Cathedral of c.575 in Georgia is perhaps the oldest example in that country. The Armenian and Georgian examples are later than some others but a distinctive and sophisticated form of the plan. They are similar to the cross-in-square plan, but in Georgia the corner spaces, or "angle chambers", are only accessible from the central space through narrow openings, and are closed off from the apses (as at
Jvari monastery, see plan above). In Armenia, the plan also developed in the 6th century, where the plan of
St. Hripsime Church, Echmiadzin (618) is almost identical to Jvari. 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, as at the ruined mid-7th century
Zvartnots Cathedral. The ruined so-called Cathedral of
Bosra, of the early 6th century, is the earliest major Syrian tetraconch church, 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
Bramante's first design for the
Basilica of St. Peter, Rome. File:Plan of S. Lorenzo in Milan.jpg|Plan of
Basilica of San Lorenzo, Milan, 370 File:Hripsime Church plan.png|Plan of
Saint Hripsime Church, Armenia, 7th-century File:SaintPierre.svg|
Bramante's plan for
St Peter's Basilica, 1503–06 File:Sv. Sava osnova.jpg|Floorplan of
Saint Sava, Belgrade, 2004 ==Triconch==