The Maze-like Square in Montauban

Our brief stay in the Tarn ended with a very pleasant meal at a Mexican restaurant in Montauban--we explored the city a bit that evening, and I found the "place" (square) very striking. Apparently there used to be a market here long ago, and the merchants would set their goods on the floor, and were able to monitor them through a hole in the floor (at least, I believe that's the story--it's possible I misunderstood, my French isn't flawless hehe).