The location on yelp is way off. It took us awhile to find the entrance to the cryptoporticos, even though it was on all of our tourist maps. The problem is that there is no signage if you're standing in the République square.
If you're standing in the square, look for the building that says Hotel Ville. Go inside. It's not a hotel. You'll find the entrance to to cryptoportico there.
The entrance lady scanned our city passes and gave us a laminated info sheet. We walked down some stairs and then all the way around and back.
It's kinda dark, wet and creepy. Other than that, there's nothing much down there. It's kind of a cool concept, but there is t really much to see. We were done in about 15 minutes. read more