The Tweed Courthouse (also known as the Old New York County Courthouse) is a historic courthouse building at 52 Chambers Street in the Civic Center of Manhattan in New York City, New York, U.S. It was built in the Italianate style with Romanesque Revival interiors. William M. "Boss" Tweed – the corrupt leader of Tammany Hall, a political machine that controlled the New York state and city governments when the courthouse was built – oversaw the building's erection. The Tweed Courthouse served as a judicial building for New York County, a county of New York state coextensive with the New York City borough of Manhattan. It is the second-oldest city government building in the borough, after City Hall.
The structure comprises pavilions to the east and west of a central section, as well as a rear wing to the south. Architect John Kellum and political appointee Thomas Little designed the first portion of the building, which was constructed from 1861 to 1872. Construction was interrupted in 1871 when Kellum died and the corruption involved in the building's construction was exposed to the public. The project was completed by architect Leopold Eidlitz, who added the rear wing and finished the interior between 1877 and 1881.