I was searching for the usage of a small construction on the edge of the Versailles Castle gardens (the stone thing on the left on the picture below, one of the gates (Saint-Antoine) is on the right):
It is located far from the castle, near the Queen's village:
I found out that this is a wash-house (which ends decades of wondering about that each time I passed next to it and always forgot to check).
This raised another question, though. Versailles was known for its lack of hygiene but the king and its court were changing shirts several times per day, which required massive washing.
Why would there be a single, small wash-house located over there? I did not see any others in the Versailles gardens, so I do not think it would be for the usage of someone leaving next to the gates. It is way to small to be the official one for the castle either.