Mesa Verde is the only American national park that protects man-made structures, as opposed to natural features. In hilly, inaccessible country south of Cortez, there are over 4,000 historic ruins, many of them large structures built under steep, overhanging cliffs in narrow canyons. This is the most famous and highly visited archaeological site in the US, due to the number, the size and the excellent state of preservation of the buildings, together with their scenic location.
The park is fully open for only seven months of the year (April to October) owing to the large amount of winter snowfall received by this high elevation location - the access road runs along a ridge at over 8,000 feet. Mesa Verde is close to Four Corners, the only point where four states meet, and the center of former Indian civilisations - many other important sites are preserved nearby including Aztec Ruins, Canyon de Chelly, Chaco and Hovenweep. Today, most of the region is still within Indian reservations; the Ute in Colorado and the Navajo in AZ, NM and UT.