Hueco Tanks State Park and Historic Site.
Here's what TPWD says about the park:
This 860.3-acre park is named for the large natural rock basins or "huecos" that have furnished a supply of trapped rain water to dwellers and travelers in this arid region of west Texas for millennia.
A unique legacy of lively and fantastic rock paintings greets the visitor at the "tanks." From Archaic hunters and foragers of thousands of years ago to relatively recent Mescalero Apaches, Native Americans have drawn strange mythological designs and human and animal figures on the rocks of the area. The site's notable pictographs also include more than 200 face designs or "masks" left by the prehistoric Jornada Mogollon culture. Hueco Tanks was the site of the last Indian battle in the county. Apaches, Kiowas, and earlier Indian groups camped here and left behind pictographs telling of their adventures. These tanks served as watering places for the Butterfield Overland Mail Route.
Because of the delicate ancient rock art, visitation is limited to protect it...but don't let that discourage you from visiting. Just plan ahead and make a reservation with Texas Parks and Wildlife, the agency that manages the park. The park is so popular, without a reservation you may not gain entry!
For other regional hiking information, visit: www.texasmountaintrail.com/hike