El Morro National Monument - http://www.nps.gov/elmo

Rising 200 feet above the valley floor, this massive sandstone bluff was a welcome landmark for weary travelers. A reliable waterhole hidden at its base made El Morro (or Inscription Rock) a popular campsite. Beginning in the late 1500s Spanish, and later, Americans passed by El Morro. While they rested in its shade and drank from the pool, many carved their signatures, dates, and messages. Before the Spanish, petroglyphs were inscribed by Ancestral Puebloans living on top of the bluff over 700 years ago. Today, El Morro National Monument protects over 2,000 inscriptions and petroglyphs, as well as Ancestral Puebloan ruins.