Organ Pipe National Monument is a westward drive out of Tucson on State Route 86. As you pass Kitt Peak and the town of Why you turn South to meet up with the Monuments visitors center. It is about 5 miles north of Lukeville, which is a small boarder town just before Mexico. If you head that direction make sure to stop at the visitors center for hiking information and map. The park is 330,000 acres of volcanic rock containing over two dozen species of cactus. The one worthy of note is the magnificent Organ Pipe.
Once you encounter these cacti it will be apparent why they are so appropriately named “organ pipe”. The columnar cactus is collection of pipes resembling the instrument. It rivals the saguaro in height. Like the saguaro, organ pipes cannot be found growing naturally in any other part of the world.
This area gets rather warm in the summer months. I recommend traveling the trails in the spring through fall. The Bull Pasture trail is a somewhat strenuous 4.1 mile loop that moves into the Ajo Mountains. The trailhead is just across from the visitors center.