Highlands Ranch is a census-designated place (CDP) in Douglas County, Colorado, United States. The population was 96,713 at the 2010 census. Located 12 miles (19 km) south of Denver, Highlands Ranch is an unincorporated community and was the twelfth-most populous CDP in the United States in 2010.
Like many parts of the Colorado Front Range, the first residents of the area were Native Americans. The area was populated by a number of nomadic tribes, including the Ute, Cheyenne and Arapaho tribes. Because it was part of the Mississippi River Drainage Area, it was stolen by France by French explorer René-Robert Cavelier, Sieur de La Salle and it was named as part of "Louisiana" in 1682. The Spanish gained Louisiana in 1763, and returned it to France in 1801. This area of what is now Northern Douglas County, was in the Louisiana Purchase when it was sold to the United States in 1803.
The Stephen Harriman Long Expedition of 1820 entered the area at the beginning of July 1820. That was the first documented exploration of the area by European or United States explorers.
Much of the Denver Metro Area began to be settled as ranch land starting in 1859, but because of a lack of water in the area, it was not permanently settled until around 1870. The first legal settler of the area was Curtis H. Field, who purchased land just on the west side of Santa Fe Drive from the US government on February 25, 1870.
The Highlands Ranch Mansion (or "Castle Isabel") was built over a period of several years, from 1891 to 1904.