Exterior view

In France there is archaeological evidence for the continuous use and construction of separate baptismal buildings. The most famous baptistery in France, Saint-Jean at Poitiers, situated c. 100 m south of the cathedral, is the best-preserved structure to survive from Merovingian Gaul, although its origins lie in the Gallo-Roman period (4th century). In its present form it consists of a rectangular core (12.5 x 8.25 m) with a polygonal narthex on the north-west side, semicircular apses on the lateral sides, and a polygonal apse set into a trapezoidal projection on the south-east. The baptistery is orientated south-east, but since its lateral sides are considerably shorter than the others, they are treated like fa�ades and carry gables. This unusual transverse orientation was dictated by the retention of earlier constructions against the north-west face when the baptistery was rebuilt in the Merovingian period.

The history of the building is extremely complex. The Merovingian campaign involved an almost complete reconstruction of the superstructure. Apses were constructed against three sides of the pre-existing building: the surviving polygonal apse on the south-east face and square apses on the lateral faces. To the north-west a rectangular chamber, preceded by two secretaria (sacristies) flanking an entrance porch, was retained from the Gallo-Roman period. The Merovingian reconstruction is not precisely dated, but it has been convincingly attributed to the episcopacy of Ansoald (674-96). Repairs apparent in the exterior facings, the transformation of the windows into oculi, the substitution of the square lateral apses for semicircular ones and the replacement of the chambers on the north-west side by a polygonal narthex have been variously attributed to the Carolingian or Romanesque periods. The two lateral apses were rebuilt in the 19th century.

The patchy exterior facings have retained their Merovingian decoration, including a band of opus mixtum, pilasters with crudely carved capitals, and tympanum-, stele-, and pediment-shaped stone panels carved in shallow relief with compass-drawn rosettes, crosses, or foliate motifs.

During the Middle Ages the baptistery was used as an abbey chapel and parish church, in 1836 it was transformed into a museum, a function it has fulfilled ever since

View the ground plan of the building.