St. John's Church was built between the 12th and 16th centuries, though there must have been churches preceding it. It was heavily damaged during World War II, but it has been restored. The oldest part of the building is the Romanesque tower. The tower dates from the early 13th century.
The choir, in part likewise from the 13th century, is a mixture of Romanesque and Gothic elements, and features two side chapels. To the left of the choir is the vestry, above which there is a room that must once have served as a chapel.
The 14th-century nave is now quite low, as it is covered by a modern ceiling inspired by that of the vestry.
The chapel to the south of the nave dates from the 15th and 16th centuries. Its two bays have Gothic vaults. The vaults of the northern aisle, which an inscription dates 1513, are flamboyant Gothic.
References:The Château de Foix dominates the town of Foix. An important tourist site, it is known as a centre of the Cathars. Built on an older 7th-century fortification, the castle is known from 987. In 1002, it was mentioned in the will of Roger I, Count of Carcassonne, who bequeathed the fortress to his youngest child, Bernard. In effect, the family ruling over the region were installed here which allowed them to control access to the upper Ariège valley and to keep surveillance from this strategic point over the lower land, protected behind impregnable walls.
In 1034, the castle became capital of the County of Foix and played a decisive role in medieval military history. During the two following centuries, the castle was home to Counts with shining personalities who became the soul of the Occitan resistance during the crusade against the Albigensians.