Hotel de Ville (City Hall), Versailles
The current City Hall in Versailles was ordered built in 1899 by the Mayor Edouard Lefebvre. Designed by Henri Le Grand, its inauguration was November 18th, 1900.
I don’t know if travelers can look inside (I assume they can) but with the palace being so huge, who has time? The palace of Versailles is the first priority.

