“This is a real nice crack—it’s my favorite,” remarks Austinite James Crump, as he gazes up appreciatively at a 140-foot-high, 3-inch-wide crack where the original west side of the University of Texas’ Memorial Stadium meets the 1973 upper deck. Memorial Stadium is the object of Crump’s affection not just because it houses his favorite football team but also because the 31-year-old rock climber has on several occasions inched his way up its dead-vertical gap without the aid of ropes, footholds, or handgrips. When the rest of us come up against a concrete wall, we look for the nearest door, but Crump sees a challenge he has to come to grips with.

To city-bound climbers like Crump, “buildering” has become an irresistible substitute for “bouldering”—scaling rocks to hone mountain-climbing skills. “Buildering is for people desperate to climb when nature hasn’t offered anything,” says Crump, who is a systems administrator for Texaco Chemicals. In some instances, both natural and man-made structures fall short, which accounts for the recent craze of manufactured climbing. Here, the upwardly mobile whittle handholds or epoxy rocks to walls or the undersides of bridges. But when it comes to altering natural surfaces, Crump objects: “Good climbers should want to rise to the rock’s challenge, not bring the rock down to a lower level.”

Austin is a buildering mecca, partly because it’s a college town, Crump says. The city’s network of creeks assures an abundance of bridges, and its geological composition means that many structures are made of eminently climbable native limestone and granite. Crump has scaled Jester dormitory and the Perry-Castañeda Library at UT, the Capitol, and all of Austin’s malls. Houston, he says with a wince, is a rock climber’s nightmare—“too much chrome and steel.”

Like a participant in hand-to-hand combat, the six-two Crump assertively approaches the stadium wall and perfectly slots his hands one above the other in the accommodating crevice. By cupping each palm, spreading his fingers, and using his thumbs as a wedge, Crump expands his hand surface just enough to maintain his 210-pound frame in a monkeylike balance. His feet are poised toe-first in the crack. As he grasps the crack and steadies himself with his feet, hoisting himself to the top is easy—barring the appearance of the university police, who are headquartered in the stadium. Even though there is no law against buildering (still, an irate property owner may decide to press trespassing charges), the police don’t approve of Crump’s means of ascent. So the state’s hundreds of builderers tend to be discreet: The undersides of bridges, including a well-traveled one that Crump refers to as a “mystery structure,” afford climbing opportunities that are unnoticed by motorists speeding by overhead.

James Crump’s tattered, callused, and slightly spatulate fingers testify to the two decades he has been climbing. “I saw a mountain-climbing show on television when I was five and knew that was what I wanted to do,” he recalls. “When I was seven I started climbing limestone cliffs near where we lived in Austin.” As Crump got older, certain genetic advantages presented themselves: A sweeping six-foot-seven-and-three-quarter-inch arm span meant that he could comfortably manage the precisely athletic, almost martial maneuvers required to reach minute extrusions on crackless surfaces, such as walls and boulders.

Builderers in action most resemble modern dancers face to face with an enormous immovable object. At one of Crump’s preferred hangouts—an inconspicuous bridge spanning Waller Creek at San Jacinto and Martin Luther King, Jr., Boulevard—the mountaineer adroitly demonstrates that the height of a climb is never a measure of its difficulty. Gently arching about nine feet high, with square-foot-size sandstone keystones, the modest bridge has a climbing route called Arch Enemy by the many who have tried and failed to crawl up and across the deceptively unpretentious span. Crump is an old hand at this challenge, and familiarity has bred respect. His most serious climbing injury happened here after he lost his balance and was left dangling by his left hand—a ripped bursa in his shoulder required extensive reconstructive surgery. After he dredges his hands in the gymnastics chalk he carries in a pouch swinging from his belt, Crump embraces the rock. He deftly pinches a tiny edge between his right thumb and first two fingers, then buoys his feet on a infinitesimal ledge. The rubber on Crump’s balletically delicate boots clings to the face of the keystone blocks, but it is also hard enough to stop on a dime if Crump slips. Splayed out against the granite, arms and feet akimbo, sweat beading on his forehead, Crump makes it about a third of the way in just a few seconds before he drops down, saying, “I’m not in good enough form to do this.”

Less grueling are two 20- by 25-foot boulders at the Southwest’s first publicly supported bouldering park. The unprepossessing site in Austin’s hilly Bull Creek Park—defined by a 60-foot-long bed of gravel to cushion falls—is the result of Crump’s lobbying efforts. Now on the Austin Parks and Recreation board, Crump is determined to see his lifelong passion shared by others. “We practice for bigger climbs here. On just one of the park boulders are forty-two different approaches to an ascension,” he explains. He is priming himself for a trip next summer to climb the formidable mountains in the Cirque of the Unclimbables near the Arctic Circle. Grappling with the challenges of the little arch on the San Jacinto bridge gives Crump a leg up on those larger challenges.