One of my favorite little national parks is Hovenweep National Monument. It is a quiet little area in the Four Corners part of Utah. It is one of the few campgrounds I actually enjoy visiting.
Most of the towers and buildings of Hovenweep Castle and the Square Tower Group were built by the Ancestral Puebloans (Anazasi) in the 1200s. Probably a few hundred people lived and farmed around this village site, and this was but one of many pueblo villages in this region. The purpose of the towers, though, remains a mystery. Theories, whether they were used for living, observation, signaling stations, ceremonies, storage, or defense, all abound. Perhaps they were used for a combination of these?
People lived in this area for perhaps thousands of years before building the towers, and then by the end of the 13th century, the site was mysteriously abandoned.