Red Rocks

The most famous concert venue in Colorado was not designed by an acoustician but by deep time. Red Rocks Amphitheatre, west of Denver, is cradled between two towering monoliths of red sandstone known as Ship Rock and Creation Rock, each hundreds of feet tall. The rock belongs to the Fountain Formation, sediment eroded from an earlier range of ancestral Rockies and laid down roughly three hundred million years ago, then tilted skyward during the same Laramide uplift that raised the Garden of the Gods and the Flatirons.

Near the top of the seating, a plaque marks a striking contact where far older Precambrian rock meets the much younger Fountain Formation. The natural bowl between the two great slabs produces acoustics that have stunned performers for a century. The opera singer Mary Garden, performing there in nineteen eleven, said she had never found more perfect acoustic properties in any opera house in the world.

Engineers credit the effect less to the composition of the stone than to the size and angle of the walls, which hold sound inside the amphitheater without letting it bounce around into a muddy echo. The seats themselves sit on stone that predates the dinosaurs.