Central City/Black Hawk Historic District
The Central City/Black Hawk Historic District is a National Historic Landmark District that encompasses Central City and Black Hawk, Colorado.  They are adjacent former gold mining camps in the Front Range of the Rocky Mountains in Gilpin County, Colorado, United States.  For a time, the area was known as the Richest Square Mile on Earth.

The district was designated a National Historic Landmark on July 4, 1961.

History
On May 5, 1859, John H. Gregory discovered a rich deposit of gold in hard rock, the first such discovery in the Rocky Mountain region.  Thousands of miners flooded into Gregory Gulch in the next few months in the Pike's Peak Gold Rush.  Several mining camps were thrown up near the Gregory Lode, and these camps eventually coalesced into Central City and Black Hawk.  The area around the Gregory Lode quickly came to be known as the Richest Square Mile on Earth.  By the time the Territory of Colorado was formed on February 28, 1861, Central City was already the largest city in the entire territory, though it lost out to Denver for State Capital.

Recently, the area has approved casinos and has seen a resurgence in attention and funds as a result.