Celtic and Early Christian

It is almost certain that the builders of the Celtic church in Ireland had access to the writings of Vitruvius. They had no way of knowing the buildings of Greek and Roman antiquity that he describes but, since they wrote and made copies of manuscripts of every kind, they will have encountered his ideas. They could make sense of his ideas about the monumental quality appropriate to a temple and apply them, where they could, to the design of their own churches.

Celtic churches are small. They are plain, stone-built structures, rectangular in plan, with simple yet carefully controlled lines. The earliest have 'battered' walls, that is they slope inwards gently, and they are built with care to create a smooth, clear line that is remarkable considering the use of rough undressed stones as the primary building material. Like the walls, the roofs are of stone built in the shape of a high triangle and vaulted on the interior.

A feature which comes from Vitruvius is the use of inclined jambs, which, like a Greek temple, makes the sides of the door slightly wider at the bottom than they are at the top. This tapering may be noted in the window openings, which had no glass, are always narrow and splayed on the inside to give light to the interior. A gently tapering line, beautifully controlled, is also the distinguishing feature of the round towers of Irish early Christian monasteries. Sometimes the lintel above the door is decorated with figure carving and the end walls of the church can project forward, as 'antae' from the face of the gable end.