Erected by the famous architect Viollet-le-Duc in 1854 in a neogothic style, St Gimer stands on the site of the former barbican of the Counts' Castle. The barbican had been demolished in 1826, and its stones sold by public auction.
The church is classified World Patrimony as well as the Cité, because it is considered as a part of Viollet-le-Duc's works, and as such has a very important historical and architectural value.
There is a high semicircular wall surrounding St Gimer's choir. This the only remains of the barbican, which was an enormous tower (60 metres circumference) linked to the Castle by the "covered passage".
"Covered" in the medieval language meant "protected". This way down from the Castle to the barbican was protected by two high walls, that still exist.