Atop the Tiffany & Co. building in Manhattan, a tri-level addition with double-height and column-free spaces wrapped in two different glass facades will replace an office extension built in 1980.

McLaren Engineering Group and Orange County Ironworks cooperated “to develop unconventional methods of crane engineering” and work within a tight site, says Jon Skinner, McLaren vice president of construction engineering.

The solution was to lift a 130-ton LTM 1140 crane seven stories to the roof, using a 500-ton Liebherr 1500 crane, he says. Designed by architect OMA, the project includes interior upgrades of the structure, built in 1940, and is set to complete in spring 2022.