In ancient Rome, the basilica stood on the main square (forum) and played the role of a market and court hall. By imitating the basilica, they spread throughout the territory of ancient Rome. Over time, the basilica also came to be called the largest, representative room in the villas of the Roman aristocracy.
Ancient secular basilicas were built as single or multi-nave buildings on a rectangular plan, open or covered, single-story or multi-story, often with an apse. One of the best-preserved basilicas of this type is the Constantine Basilica from the 4th century in Trier. Due to the location of the entrance, they are divided into basilicas:
- oriental with an entrance (or entrances) on the long sides and an interior with a central nave and aisles,
- Greek with an entrance on one of the short sides and with an apse opposite the entrance.
Christians, unwilling to use pagan temples or build buildings similar to them, adopted the Greek basilica as their model. The basilica system was in force throughout Christian architecture. Already in the 4th century, a wooden sloping roof truss, open or separated by a wooden ceiling, was introduced.