A thousand ways up the rock

From the air the canyon reads as two red walls with a thread of water between them. South Boulder Creek runs the floor, cold and fast off the Front Range. The rock is Fountain Formation sandstone — banded conglomerate, tilted and stacked in strips that climbers compare to bacon laid against the cliff. Roughly nine miles south of Boulder, and already a different country.

This is one of the most concentrated trad-climbing grounds in the United States: more than a thousand established routes on formations named the Bastille, Redgarden Wall, and the Wind Tower. Trad means the protection is removable — cams and nuts wedged into cracks, nothing bolted to clip. Most of the classic lines were written in the 1950s and ’60s by Layton Kor, Pat Ament, and Jim Erickson. From overhead you can pick out the belay ledges and small figures on walls that run close to 700 feet.

The canyon drew crowds long before the climbers. The Eldorado Springs resort opened on the Fourth of July, 1905, fed by artesian springs under the cliffs. Its concrete pool, finished in 1906, was once advertised as the largest in the country — the “Coney Island of the West,” reached by rail from Denver and Boulder. The pool still runs on spring water and reopened in 2024 after a long restoration.

The best story is overhead too. Between 1906 and 1948, the aerialist Ivy Baldwin walked a steel cable strung from the top of the Bastille to the Wind Tower, hundreds of feet above the creek. He made the crossing more than eighty times. His last was in 1948, on his eighty-second birthday. Fly the same gap now and it is only air — but from above you understand exactly what he was standing on.