The Old Courthouse, Warren County, also known as Warren County Courthouse, stands prominently on a hill in Vicksburg, Mississippi, and was a symbol of Confederate resistance during the Siege of Vicksburg. It was designated a National Historic Landmark in 1968 and a Mississippi Landmark in 1986. The landmarked area comprises the entire Courthouse Square, which includes the courthouse and four attached buildings that were originally cistern houses for catching rainwater to fight fires, but these were later converted into offices.

Vicksburg is a historic city in Warren County, Mississippi, United States. It is the county seat. The population was 21,573 at the 2020 census. Located on a high bluff on the east bank of the Mississippi River across from Louisiana, Vicksburg was built by French colonists in 1719. The outpost withstood an attack from the native Natchez people. It was incorporated as Vicksburg in 1825 after Methodist missionary Newitt Vick. The area that is now Vicksburg was long occupied by the Natchez Native Americans as part of their historical territory along the Mississippi. The first Europeans who settled the area were French colonists who built Fort Saint Pierre in 1719 on the high bluffs overlooking the Yazoo River at present-day Redwood. They conducted fur trading with the Natchez and others, and started plantations. During the American Civil War, it was a key Confederate river-port, and its July 1863 surrender to Ulysses S. Grant, along with the concurrent Battle of Gettysburg, marked the turning-point of the war.