Time Out says
For centuries, the main source of drinking water in Paris was the Seine, which was also the main sewer. Construction of an underground sewerage system began at the time of Napoleon. Today, the Egouts de Paris constitutes a smelly museum; each sewer in the 2,100km (1,305-mile) system is marked with a replica of the street sign above. The Egouts can be closed after periods of heavy rain.
Entrée face au 93 quai d'Orsay, Pont de l'Alma
|Transport:||Métro : Alma-Marceau ou Invalides|
|Price:||Admission €4.30; €3.50 reductions; free under-6s|
|Opening hours:||May-Sept 11am-5pm Mon-Wed, Sat, Sun. Oct-Apr 11am-4pm Mon-Wed, Sat, Sun|