In the early 4th century Eusebius used the word basilica () to refer to Christian churches; in subsequent centuries as before, the word basilica referred in Greek to the civic, non-ecclesiastical buildings, and only in rare exceptions to churches. Churches were nonetheless basilican in form, with an apse or tribunal at the end of a nave with two or more aisles typical. A narthex (sometimes with an exonarthex) or vestibule could be added to the entrance, together with an atrium, and the interior might have transepts, a pastophorion, and galleries, but the basic scheme with clerestory windows and a wooden truss roof remained the most typical church type until the 6th century. The nave would be kept clear for liturgical processions by the clergy, with the laity in the galleries and aisles to either side. The function of Christian churches was similar to that of the civic basilicas but very different from temples in contemporary Graeco-Roman polytheism: while pagan temples were entered mainly by priests and thus had their splendour visible from without, within Christian basilicas the main ornamentation was visible to the congregants admitted inside. Christian priests did not interact with attendees during the rituals which took place at determined intervals, whereas pagan priests were required to perform individuals' sacrifices in the more chaotic environment of the temple precinct, with the temple's facade as backdrop. In basilicas constructed for Christian uses, the interior was often decorated with frescoes, but these buildings' wooden-roof often decayed and failed to preserve the fragile frescoes within. Thus was lost an important part of the early history of Christian art, which would have sought to communicate early Christian ideas to the mainly illiterate Late Antique society. On the exterior, basilica church complexes included cemeteries, baptisteries, and fonts which "defined ritual and liturgical access to the sacred", elevated the social status of the Church hierarchy, and which complemented the development of a Christian historical landscape; Constantine and his mother Helena were patrons of basilicas in important Christian sites in the Holy Land and Rome, and at Milan and Constantinople.