Well named, Thimble Peak looks a lot like a giant sewing thimble placed high on the big ridge that separates Sabino and Bear Canyons in the Santa Catalina Mountains north of Tucson. Thimble occupies a prominent position, and once recognized can be seen from most places in Tucson as well as from some sections of the Mt. Lemmon Highway. None the less, Thimble’s summit is not often visited. No trails reach the peak, it is guarded by tall cliffs on many sides, and reaching the true summit requires a few sections of rock climbing.
Source = http://blog.summithut.com/post/2010/02/24/Thimble-Peak.aspx