Rue des Rosiers No. 4: Hammam St. Paul

Just as you enter Rue des Rosiers, on the right at No. 4, you'll find a store of the Swedish fashion brand COS. The building was once a public bathhouse, and the words "Hammam St. Paul" are still written across its upper facade.

Remember how bad Paris's water and sewage systems were until the late 19th century? Walking through the historic districts, it's hard not to keep coming back to the city's grimy past of foul smells and filth in the streets. Before the 20th century, very few homes had a bathroom, and having one was a sign of serious wealth. So where did Parisians wash? At the fountains and drinking taps scattered around the city, or in the Seine.

Toilets were even worse. Emptying chamber pots out of the window was common, and even fine houses had toilets that were little more than holes in the wall, leaving waste to pile up in the street. Picture those narrow alleys. It's easy to see why people say high heels came about to keep feet out of the muck and perfume to mask the stench.

Alarmed by the state of public hygiene, France began installing public toilets and, starting with districts packed with workers, building public showers and bathhouses. Hammam St. Paul was one such bathhouse, opened in the Marais in the late 19th century. Many 19th-century shower and bath buildings still survive across Paris. Some, like this clothing store, have been reborn as shops, restaurants or exhibition spaces, while others still operate as public hygiene facilities today.