Just at the western edge of San Ignacio, on a tall hill, is a small, intriguing Mayan site, the unfortunately named Cahal Pech ("Place of the Ticks"). You probably won't be bothered by ticks now, however. It was occupied from around 1200 BC to around AD 900. At its peak, in AD 600, Cahal Pech was a medium-size settlement of perhaps 10,000 people with some three dozen structures huddled around seven plazas. It's thought that it functioned as a guard post, watching over the nearby confluence of the Mopan and Macal rivers. It may be somewhat less compelling than the area's other ruins, but it's no less mysterious, given that these structures mark the presence of a civilization we know so little about. Look for answers at the small visitor center and museum.