Byzantine Churches in Constantinople
Of the Cross church plan showing the cross externally at the ground level no example survives in the city. But at least one church of that form was seen at Constantinople in the case of the church of the Holy Apostles. This was essentially a mausoleum, built originally by Constantine the Great and reconstructed by Justinian to contain the sarcophagi of the sovereigns and the patriarchs of New Rome.
The church of S. Mark at Venice was built on the plan of the Holy Apostles. It is a cruciform church with aisles, but the galleries which might have been expected above them are omitted. The central dome rests on four piers, and four smaller domes cover the arms.
Professor Strzygowski gives examples of cross-planned cells in the catacombs of Palmyra, and in many Eastern rock tombs. Such cross plans are found also in the Roman catacombs. These subterranean chapels, of course, do not show the external treatment, yet there can be little doubt that