The Chapelle Saint-Louis de Carthage was a small Roman Catholic chapel built in 1840 by the French — well before the formal French protectorate over Tunisia — to mark the supposed site of the death of King Louis IX during the Eighth Crusade in 1270. It was the precursor to the much larger Acropolium of Carthage on the Byrsa hill above and reflects the French colonial fascination with both Carthage as Crusader battleground and Saint Louis as patron of French Catholic Tunisia.
The chapel was deconsecrated after Tunisian independence and is no longer open to the public, but the small classical-style stone building is still standing at the foot of Byrsa hill and is visible from the road. The site is on most route maps of historic Carthage; combine with a visit to the Carthage National Museum just up the hill.