La Piedra Escrita (Carr. 144, km 7.3, 787/828- 1241, free) is one of Puerto Rico’s most revered reminders of the island’s Taíno culture. The enormous granite boulder measures 32 feet high and 13 feet wide and is located smack-dab in the middle of Río Saliente, creating a natural pool where visitors can go for a swim.

But it’s what’s on the boulder that is of interest to historians and archaeologists. On the rock’s surface are 52 petroglyphs that were carved into the rock by members of indigenous groups sometime between A.D. 600 and 1200. Some of the symbols clearly depict faces of humans and animals while others are geometric or abstract in shape. Because of the quantity of petroglyphs on the rock, some believe La Piedra Escrita was an important ceremonial site, but its significance is ultimately unknown.

Today La Piedra Escrita is a popular tourist sight. A long series of wheelchair-accessible switchback ramps have been built that descend from the stone escarpment overlooking the river down to the water where visitors can get a close-up look at the rock and go for a dip. It’s a popular picnic spot on weekends.