Located in the northernmost reaches of Pakistan, the Trango Towers, a family of rock towers soaring high above the Baltaro Glacier in the Gilgit-Baltistan region, are said by even the most seasoned of rock climbers to be among the most difficult vertical ascents in the world.Great Trango, the tallest formation in Trango Valley, features 4,396 vertical feet of granite, more than any other face in the world. This spire is over 20,000 feet above sea level, and combined with Trango Tower (aka Nameless Tower) to the northwest, these formations dominate the horizon on the approach to the larger mountains of K2, Broad Peak, Gasherbrum IV, and Nanga Parbat.Best climbed between June and September, the cracks in the compact granite are “like Yosemite with a bit of dirt in the eye,” says Josh Wharton, who, with Cordes, established the southwest ridge of Great Trango. Their 2004 ascent of the Azeem Ridge (VII 5.11X M6 A2) required a 50-mile hike into basecamp and 7,400 vertical feet of climbing over four and a half days.