The Hudson County Courthouse or Justice William J. Brennan Jr. Courthouse is located in Jersey City, Hudson County, New Jersey, United States. The six-story structure was originally built between 1906 and 1910 at a cost of $3,328,016.56. It is considered to be an outstanding example of the Beaux-Arts architectural style in the United States.
The courthouse was used as the primary seat of government for Hudson County from its opening on September 20, 1910 until the construction of the Hudson County Administration Building in 1966. The courthouse was vacant for many years and was scheduled for demolition. The building was added to the National Register of Historic Places on August 25, 1970. Restoration began in the mid-1970s, and the building was reopened in 1985. In 1984, the Hudson County Board of Chosen Freeholders renamed the building in honor of Supreme Court Justice William J. Brennan Jr. The restoration of the courthouse was acknowledged by a Victorian Society in America Preservation Award in 1988.