El Morro National Monument in western New Mexico preserves a sandstone promontory that served for centuries as a landmark and watering place along the old Zuni-Acoma Trail. At its base is a reliable pool of water, and above it stand the remains of a large Ancestral Puebloan settlement occupied between about 1275 and 1350 AD by as many as 600 people in roughly 355 rooms. The cliff is famed for inscriptions left by travelers from different cultures, including Juan de Oñate’s dated 1605 inscription, later 19th-century names, and earlier Puebloan petroglyphs. Protected federally in 1906, the site also includes pueblo ruins, trails, and a preserved dark night sky.