Try to read the book in advance. It puts things into perspective,especially if you do visit some of the catacombs. I could not cope with them due to my claustrophobia, but because I had read the book I felt truly dreadful that I could not cope. Those people had no choice if they wanted to survive and the catacombs then we're not nicely painted white and clean smelling!! Sadly the enclosed space won my mind and I had to come out, but my husband managed a longer visit. Still well worth while to me though! Truly make you think!
Enjoy your visit.