Conclusion: the Christian basilica in contemporary Roman architecture. In fact all these theories seem pointless: the Roman architect of the 4th c. already had available to him a type of building intended for assemblies, i.e., the basilica, which was commonly adapted to other uses and was not just an annex of the forum. All that was needed was to modify the plan and in particular to arrange it on an axis, with a focal point provided by the altar or sacred tomb, to suit the requirements of worship whereas the prototype required no special orientation. The only hesitation would have been between two methods of roofing. As well as the trussed basilica, there had been built in at least one isolated instance the basilica of Maxentius or of Constantine at Rome a large vaulted hall of the type commonly used for the frigidara of public baths.
This type of roofing, requiring competent engineers and skilled labor, was adopted by Christian architecture for large buildings only very late and with a different plan. Who took the initiative of choosing and modifying the plan? The clergy or the emperor? It is hard to say. But to the extent that the great Constantinian foundations utilized public or legally protected lands e.g., the Vatican cemetery and required considerable imperial financial subsidies, intervention by court architects is likely, at least for the main cities and in the Holy Land. Yet we have seen that the buildings constructed in that period were of various types in Rome itself, and the differences are even more marked from one region to another see below.