Square Tower Group in Hovenweep National Monument, Utah, USA

The Milky Way is especially bright among the hills, canyons and prehistoric towers of Hovenweep National Monument on the border of Colorado and Utah in the United States. Hovenweep is so remote that almost no artificial light disturbs the star-filled skies. These views are not much different from those seen by the Ancestral Puebloans who built these towers. They were a farming culture who first settled in the area roughly 1,100 years ago. By the late 1200s, there were around 2,500 people and they had built these towers and others in six different villages. Some of these buildings may have been used as defensive fortifications, storage areas and homes. But researchers suggest that the tower called Hovenweep Castle, seen here, was probably used as a celestial observatory.
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