The term "basilica" was first employed by Constantine in 325. The oldest form of a Christian church is an extended rectangle that resembles the Noah's Ark and the Solomon's Temple. It originated from the Roman multi-nave structure that had most often been used as a court of law. During the early Christian period, it had developed into a multi-nave non-vaulted church, with the central nave * being higher than the side-aisles *. This higher part of the central nave contains the windows - so-called basilican lighting. It is positioned towards the East, with the entrance in the West. The church of that time consists of the three main parts: an altar, a naos, and a narthex or atrium intended for the clergy, congregation and catechumens. Various annexes with different functions had been added onto such church basis: baptistery, martyry, diaconicon, prothesis. Back in the early Christianity, the eastern side was added a cross-aisle nave - a transept. In the Middle-Byzantine period, the wooden roof structure was replaced by a vault. Basilican churches have preserved this form until now. The variety of church types has been conditioned through the centuries by different liturgical demands.