New York City Hall, located in the Civic Center of Lower Manhattan at City Hall Park, is the seat of New York City government and the oldest city hall in the United States still serving its original governmental functions. It was constructed between 1803 and 1812, designed by architects Joseph François Mangin and John McComb Jr..
The building houses the office of the Mayor of New York City and the chambers of the New York City Council. Architecturally, it blends French Renaissance style on the exterior with American-Georgian style inside. The interior features a grand marble stairway, a rotunda supported by Corinthian columns, and a coffered dome added in 1912
 
Interesting facts...
The site was once home to the notorious Bridewell Prison, and during renovations in the 1990s, bones were discovered beneath City Hall
There’s a secret, abandoned City Hall subway station beneath the building, known for its beautiful arches and chandeliers, closed to the public for decades