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. 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 los