As the Spanish extended their empire out of Mexico, they established a Presidio (fortress) along the San Pedro River in 1776. Learn about the Presidio and what happened there to make the Spanish abandon the fort in 1780.

The hike is about 3.5 miles (total) over an uneven, gravel trail that will be uphill on the return; it will take about 3.5 hours. There is no shade and it can be hot. Wear hiking shoes and a hat; bring plenty of water and a snack. Meet at the Presidio parking Area on In Balance Road off Hwy 82. Admission is free. Donations gratefully accepted.

Info: (520) 508-4445, (520) 417-6960, http://www.sanpedroriver.org/wpfspr/.