The classification of religious architecture by type was first established around the turn of the 20th century and served as a chronological taxonomy. Although this method of dating has largely been superseded, the identification and study of these types remains a useful system of basic classification. The most common plan types are the following:

 

• Basilica (e.g. Sant'Apollinare in Classe)

• Domed basilica (e.g. Hagia Eirene in Constantinople)

• Cross-domed church (e.g. Hagia Sophia in Thessaloniki) 

• Cross-in-square (e.g. the North Church of Lips Monastery in Constantinople)

• Domed octagon (e.g. Nea Mone in Chios)

• Greek cross-domed octagon (e.g. the katholikon of Daphni) 

• Ambulatory church (e.g. Pammakaristos in Constantinople)

• Triconch (e.g. the katholikon of the Great Lavra at Mount Athos)

• Tetraconch (e.g. the tetraconch church at Hadrian’s Library in Athens)

 

Many other church plan types existed, but they were less commonly employed. Most could be enlarged by the addition of enveloping spaces—exedrae, ambulatories, aisles, porches, or chapels—resulting in new compound plans and more elaborate exterior massing. Multiplication of domes (St. Sophia, Kiev) is one of the most important architectural by-products of this phenomenon.