Calder's Final Triumph:
Calder's skillful positioning of Mountains and Clouds in the Hart atrium contributes to the work's success. The placement cleverly integrates the sculpture into the towering asymmetrical interior of the building, both vertically and horizontally. Calder advocated simplicity in the design of this work, since the space presents a complex background of doors, windows, balconies, stairwells, and a coffered skylight. Similarly, by selecting a matte black surface for the entire composition, he created a bold contrast to the polished white marble of the surrounding interior walls.
The aluminum clouds were raised first, spanning 75 feet and weighing more than two tons. The installation of the steel mountains followed, reaching a height of 51 feet and weighing 36 tons.