Mesa Verde National Park is located in southwestern Colorado, about 10 miles from Cortez. It can be found off of US Route 160. It is a cultural heritage site, and is the only national park that was set aside in order to preserve something man-made; all other national parks preserve natural beauty. The park comprises 52,122 acres. For those who don't speak Spanish, Mesa Verde is Spanish for green table, although since mesa has been absorbed into English, it really means green mesa. This is odd considering that it is in a desert.
The historical information about the "discovery" of the park is adapted from the site mentioned at the bottom.
Although white settlers visited the area as early as the mid-1750s, the first explicit reference to the area came in 1859 from Professor J. S. Newberry, who was conducting a geological report for Captain J. N. Macomb, one of the many exploratory expeditions of the time. Apparently, the use of the term "Mesa Verde" was in wide use at the time, because Newberry refers to the area as such. More than likely, he didn't encounter any ruins, because none are mentioned in his report. It is unlikely that he overlooked mentioning them.
It wasn't until 1874 that there was a recorded instance of a white person entering the ruins. A surveyor for the U. S. Geological and Geographical Survey, W. H. Jackson, entered some of the ruins in September of 1874. By this time, the ruins were faily well known among prospectors in the area, and it was one of them, John Moss, that first led Jackson to the area. The two entered together. I believe (though I'm not 100% positive) that Jackson took pictures, which still exist. Although he discovered several other ruins in the area, he didn't find them nearly as impressive as the first ruins, which are today known as Cliff Palace. Another popular story has the ruins being entered first by a pair of cowboys. Sounds nice, but doesn't seem likely. They probably were responsible for discovering many of the outlying ruins though.
From this point on, most of the exploration done in the park was done by looters, looking to make a quick buck. So, in 1906, Mesa Verde was commissioned as a National Park, allowing the government to better protect the ruins. Of course, it didn't stop them, but it was a start. Today, any looters will simply visit one of the many other, unprotected ruins that smatter the desert southwest. In the four corners area, it is quite easy to find pottery shards and other artifacts that have been found.
As mentioned in the above writeup, estimates indicate that the Anasazi Indians inhabited this area for close to 700 years, and some pictographs indicate that they were there even earlier than that. See the writeups under Anasazi for more information on this mysterious group of people. Most of the cliff dwellings at Mesa Verde were built during the latter part of the Ansazi's stay at Mesa Verde, estimates have them being build in the 1200s. The cliff dwellings are certainly the most elaborate of all of the Anasazi structures at the park, and represent the peak of the technological development of the Anasazi.
The park today provides access primarily to the cliff dwellings, but most of the ruins in the park are actually on top of the mesas. Only a few of these are open to the public because they aren't terribly interesting to non-archaelogists and because they are constantly being excavated. The cliff dwellings tend to be difficult to get to, requiring tight squeezes through cliffs, or climbs down ladders. Most have walls, built by the Anasazi, to prevent the occupants from falling. Most of the buildings are similar and it is difficult to discern any difference between their functions, although most were probably houses. If you come at the right time of day, the sun can shine in through cracks in the walls and make for some incredible pictures.
The only structures that have major differences from any others are the Kivas. "Kiva" is a Hopi word that was given to the structures by white archaeologists. These are circular pits in the ground, with a ladder used to get down into them. In the time of the Anasazi, these pits had roofs on them, but these have long since caved-in (although there are a few restorations around the park). These are believed (based primarily on Hopi tradition) to have been ceremonial pits used for religious ceremonies, although the exact nature of these ceremonies is unknown. At some other parks in the area, Kivas were built entirely above ground.
Some of the most popular ruins in Mesa Verde are Balcony House, The Sun Temple, and Cliff Palace. All are heavily visited, however, and so the ruins must be protected. This has lead to the addition of cement to some ruins to protect them from tourists, especially the Sun Temple. Plus, along a lot of the rock walls you can the see oily black residue from thousands of people resting their hands. Still, the ruins are remarkably well preserved; some still have painted plaster on the walls. Of the three ruins that I mentioned, Balcony House is probably the most interesting. The sun temple is one of the few major ruins that isn't a cliff dwelling, and Cliff Palace is the largest single grouping of ruins in the park, visited by nearly everyone. It was most likely the center of whatever loose form of government existed in the area.
Within the past few years, there have been several wildfires at Mesa Verde, caused by lightning. These fires have closed the park for a while and caused some people to worry about possible threats to the ruins (although they are made of rock, so it wouldn't exactly burn them to the ground). But actually, the wildfires have helped the park's true purpose, because they have helped to reveal thousands of previously unknown ruins, allowing for much greater study of the park and the people who once lived there.
Overall, this is a nice park. If you are in the four-corners region, then it is worthwhile to stop in and see the park. If you are a history/arcaeology buff, then you will find the park particulary enjoyable. This one might not be as fun for the kids as Yellowstone, Hawaii Volcanoes National Park, or Rocky Mountain National Park, but it is still interesting and a nice visit. And if you are especially interested in ruins, there are plenty of other nearby parks and monuments that are well worth investigating.