As a contrast to our visit to Versailles we went to tour the sewers at Le Musée des Égouts de Paris. In 1964 when I went to Paris I went to the sewers tour which was very different - most of it was in a boat in the main sewer pulled by a couple of workers shouting the names of the restaurants and sights above. Now there is a museum with some interesting well-done exhibitions about the evolution of the water and sewer systems in Paris from when waste dripped into the Seine which was the source of drinking water. The tour was informative but less dramatic and macabre.
We saw flowing water, some of the machinery, a sign showing the old tour situation, an explanation how Victor Hugo knew a sewer inspector which helped him in describing the adventures of Jean Valjean, a small diorama with rats, streets signs showing what street was above.