Baptistère (baptistery)

A baptistery is an isolated part of a church containing the baptismal font.
It is obviously used for christenings.
A world famous baptistery can be found in Pisa (Italy), next to the church.
The first picture shows the baptistery Saint-Jean in Poitiers (Vienne 86), the second one the interior of the baptistery in Venasque (Vaucluse 84).

Baptistère Saint-Jean - Poitiers (86)

Baptistère - Venasque (84)