Franktown Cave is an archeological site in the U.S. state of Colorado, located 25 miles (40 km) south of Denver on the north edge of the Palmer Divide. It is the largest rock shelter documented on the Palmer Divide, which contains artifacts from many prehistoric cultures. Prehistoric hunter-gatherers occupied Franktown Cave intermittently for 8,000 years beginning about 6400 BC The site held remarkable lithic and ceramic artifacts, but it is better known for its perishable artifacts, including animal hides, wood, fiber and corn. Material goods were produced for their comfort, task-simplification and religious celebration. There is evidence of the site being a campsite or dwelling as recently as AD 1725.

Franktown Cave is a rock shelter 198 feet (60 m) above Willow Creek, a tributary of Cherry Creek that flows into the South Platte River at Denver, Colorado, 25 miles to the north. It is more than 6,000 feet (1,800 m) in elevation.

Situated on Palmer Divide, which separates the South Platte River basin from the Arkansas River basin, Franktown Cave is its largest documented rock shelter in the area. Palmer Divide is an east–west ridge in central Colorado that runs perpendicular to the Rocky Mountains between Denver and Colorado Springs and east to Limon, Colorado. Monument Hill is the highest point of the divide, at about 7,500 feet (2,300 m).

The cave was created when water eroded the soft, water soluble layers of Dawson Arkose formation through seeps below a thick, hard shelf of Castle Rock Conglomerate. The area provides two key raw materials that were used for tool-making:

Near the rock shelter, spring-fed streams traverse a land of scrub oak, plains grassland and open ponderosa pine forest.

Franktown Cave is the largest rockshelter documented in the Palmer Divide. The overhang is about 131 feet (40 meters) wide, and measures 65.6 feet (20.0 meters) between the dripline and the rear wall in the northern half of the shelter. This is where most of the excavations were placed and the majority of the artifacts were found. The shelter is naturally divided into a lower and upper shelter. The upper shelter is on the south side and the lower shelter is on the north side. Very little documented excavation has occurred in the upper shelter, because it has thin sediment cover over the bedrock and is periodically saturated with water. Very few artifacts have been found in the upper shelter.

Prehistoric cultural periods of eastern Colorado are traditionally identified as: Paleo-Indians at the earliest, Archaic, Ceramic and Protohistoric phases. Evidence of Franktown Cave habitation began with the early Archaic period (about 6400 BC) and continued through each of the intervening cultural periods to AD 1725.

People of the Archaic period moved seasonally to gather wild plants and hunt game, such as deer, antelope and rabbits. Late in the Archaic period, about AD 200–500, corn was introduced into the diet and pottery was made for storing and carrying food.