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 were built by the Ancestral Puebloans (Anazasi) in the 1200s and 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, then by the end of the 13th century, the site was mysteriously abandoned.