Javits' space had to stay functional during renovations. Tishman Construction SVP Glen Johnson tells us it first started by building the 110k SF expansion, which gave the convention center 80k SF of additional floor space. It then divided the top floor—where conventions are held—into nine slices of 45k to 70k SF, which it decommissioned in phases as work was done. In the Crystal Palace (the entryway where you register for events), a platform was built 25 feet in the air so they could work on the glass. The platform had a 500-pound per SF load to allow for work above, and looked like a finished space from below. That was kept up for two years.

It also had to replace the entire 11-acre roof, which held 89 HVAC units. But given its size, you couldn't remove the HVAC units by crane from any side of the building. So Tishman built 3.5 miles of track that connected to two landing platforms on the south and north side of the building; each HVAC unit was loaded on to a push cart, which then traveled to the edge of the building where it was removed by crane. It also worked in sections and around the convention center. "We staged the major work around the events," he says. "Construction continued behind temporary walls and the attendees didn't even know we were there." (Except for the vague sense you were surrounded by the wall-dwellers from The Borrowers.)