Early Christian Architecture - definition of architectural style

What is Early Christian Architecture?

Estimated period of occurence (100 - 700)

Style of architecture developed from the 1st century to the 6th century AD since the advent of Christianity in ancient Rome to the invasion of the barbarians. The most characteristic building of this architecture style, apart from catacombs, were the basilicas. The basilicas were built with a rectangular nave and sometimes the nave was crossed by a transept shaping the classical Christian cross. The main entrance was an atrium with a fountain, the ancestor of the cloister. Almost all the relevant buildings in this style are located in Rome.