73 WORTH STREET

Phase one was straightforward, at least on paper. There were no mechanicals under this first section of sidewalk, so it was a simple matter of replacing the vault's corroded cast-iron beams and pillars with steel I-beams, setting a metal "cue deck" on top of them, pouring and waterproofing a concrete slab, and finally pouring the sidewalk on top of it.

The structural engineer who drew up the original plans called it "the biggest and most complicated private vault job in the history of New York City." Now the 30-unit condominium The Worth Building, a former industrial loft at 73 Worth Street, had to rebuild a nearly hundred-year-old, two-story vault that covered all the underground mechanicals, waterproofing it and covering it with nearly 300 linear feet of sidewalk. The price tag was a formidable $1.6 million. But money was the least of the obstacles.