Mesa Verde National Park in Colorado is known for its ancient Puebloan cliff dwellings and ruins built between 600-1300 CE. The ruins were discovered in the 1880s and the park was established in 1906 to protect the archaeological sites. Two influential figures, Virginia McClurg and Gustaf Nordenskiold, helped raise awareness of the ruins and fight for the park's protection. The ruins were built from sandstone quarried on site and were situated in alcoves and cliff faces formed from the erosion of alternating layers of sandstone and shale.