The church at Aigremont was located in a stronghold that was destroyed in 1653 on the orders of Mazarin. It is an elongated sandstone building with a north-south orientation. The nave, dating from the 16th century, consists of three vessels with three bays of rib vaulting. The nave's three naves are covered by a single roof. A crypt, the entrance to which is at the level of the north aisle, extends under the nave. The barlong choir has a flat apse and dates from the early 13th century. Its axial bay was closed off when the high altar was installed, and the right wall is lit by a semi-circular bay. The right wall of the choir houses a three-lobed oculus, without its grille, the visible remains of a former Eucharistic cupboard hidden by the panelling. There is a projecting transept, the crossing of which supports the bell tower topped by a shingled pavilion roof. A hagioscope is built into the east wall of the north arm of the transept. The sacristy backs onto the left wall of the choir, where traces of a spiral staircase can be seen, which has now disappeared and probably once led up to the bell tower. The current access is from the outside via a straight staircase attached to the wall of the south sacristy.
Eglise Saint-Sébastien d'Aigremont
