This restored adobe fortress doubles as the western entrance and visitor center for Big Bend Ranch State Park, 4 miles southeast of Presidio. Look for exhibits about history and archaeology on-site. You can get backpacking, camping and river-use permits here.
Note – if you arrive from the east and you forget your park pass in your car in the parking lot, the ranger will give you a look…and then make you walk all the way back to your car to get it. So don't forget to bring it with you.