This designated part of the Sonoran Desert preserves more than two dozen species of cacti, including the park's namesake, as well as other desert plants and animals. Because organ pipe cactus tend to grow on the warmer, usually south-facing, slopes, you'll get the best views of them by taking either the 21-mile scenic loop Ajo Mountain Drive (a one-way, winding dirt road) or Puerto Blanco Drive, a two-way, 53-mile dirt road, of which only the first 11 miles are currently open to the public. In an effort to limit the number of cars that traverse Puerto Blanco Drive, the monument requires drivers to obtain a free permit at the visitor center. Ranger-led tours and talks are offered January through March. A campground at the monument has 208 RV (no hookups) and tent sites ($12). Facilities include a dump station with potable water, showers, flush toilets, grills, and picnic tables.