The architect of San Francisco's City Hall was a graduate of the Ecole des Beaux Arts in Paris so that's why it looks like a copy of the Hotel des Invalides. The great thing about SF City Hall is that it's part of an intact Civic Center, all designed by the same architect including the (old) Public Library, Civic Auditorium, Opera House and Veterans Memorial Building. Also Joe DiMaggio and Marilyn Monroe were married at City Hall but I guess that doesn't compare to the history of some other city halls LOL. The UN Charter was signed in the plaza between the Opera House and the Vets Memorial Building though.
I like the two old city halls in New Orleans--Gallier Hall and the Cabildo. The Cabildo is probably one of the most historic city halls in the country because the Louisiana Purchase was signed there.
Gallier Hall
The Cabildo
I also like Los Angeles City Hall.
LA City Hall
Is the US Capitol Washington DC's city hall?