Provins

Located in the departement of Seine et Marne, Provins is listed on the Unesco list of world heritage sites. It was once a very important town that hosted the largest fairs of the area and was under the protection of the counts of Champagne. 

Today, the town has a number of well preserved medieval buildings, extensive remparts and a network of subterrean caves, all which date back from the middle ages. 
The most interesting buildings are located in the upper town, though the more modern lower town also has a number of churches and half timbered houses.