While strolling along the Seine under the shadow of Notre-Dame, there are some numbered doorways. Supposedly, these used to connect the river with the houses built along the banks of the Seine. Others led to shops that were actually built into the embankment walls. As an aside, in the very old days, there were even houses built on top of all the bridges. The Pont Neuf (the “new” bridge, which is the oldest bridge now), was the first of the Seine’s bridges not to be lined with houses. 
Anyway, I digress. One of these blocked-up doors led directly into the city’s oldest hospital, Hotel-Dieu. As you stand in the square studying the façade of Notre-Dame, the building across the street to your left is the current hospital. Before the 19th century, it used to stand to your right—next to the Seine above the embankment where the statue of Charlemagne and the WCs are today. 17th century crowding at the hospital (by then over 900 years old) led to expansion of additional wards which were built over the Pont au Double, another nearby bridge.
The nuns working at the hospital used passageways to go directly from the wards down to the river where they emerged from the doorways to wash the patients’ clothing. This earned them the nickname, les petites laveuses or “the little washerwomen.” Interesting, n’est-ce pas?
