In 1672, the Augustin monks left a part of their land to the Mercy Penitents. These Penitents were called « Black Penitents » (because of the colour of their clothes). The chapel was finished in 1705 and dedicated to Saint Jean-Baptiste.
In 1791, the French Revolution put an end to the cult, the brotherhood disappeared and the chapel was used as an audience room by the new town council. Then, it became the chapel of the hospice from 1805 to 1973.
The chapel - with its painted wooden ceiling which constitutes the treasure of the building, and the magnificent altar with its early 18th c. gilt reredos (altarpieces) - was listed as an ancient monument in 1979. It was deconsecrated and renovated in the 1980s.
From 2007, the building is used as an auditorium.
Entrance only during concerts, exhibitions or conferences