National Center for Atmospheric Research

I. M. Pei, the Canton-born master of Modernism educated at MIT and Harvard, designed one of Colorado's finest complexes, sited in a Boulder mountain park. Pei, who also designed major projects in downtown Denver, appreciated the spectacular natural setting on an otherwise undeveloped mesa with foothills beyond. “We found we had to return to elemental forms,” he said. Studies of cliff dwellings at Mesa Verde and pueblos such as Taos led Pei to a loosely neo–Pueblo Revival structure using colors, textures, and massing borrowed from the setting. A nearby quarry yielded a distinctive reddish aggregate that was mixed with concrete for the walls. When it was bush-hammered, the aggregate fractured so as to give a stony look like that of the surrounding soil and the giant, upended stone slabs known as the Flatirons.