T/.dropcaphe U.S. General Services Administration has, finally, formally signed its 20-year, 270,000-square-foot lease for six floors (50 through 55) at the LEED Gold-hopeful 1 World Trade Center. The deal comes after months of waiting: GSA signed a letter of agreement for the space in October of 2011 (after signing an MOU with the Port Authority back in 2006).

In recent weeks, Senator Schumer called on GSA to finalize the deal – and even blamed House Republicans for trying to stall it and other federal leases. But in a statement yesterday the senator called the lease "a major milestone in the success story of the redevelopment of lower Manhattan. While it took some pushing and some prodding, this lease is finally signed, sealed, and delivered."

One reason for the delay was the lease's complexity. "It's so complicated because there is an insurance payment involved in it, it's like calculus," the Observer reported one source as describing the reasons for the delay in GSA finalizing the deal. Although terms were not disclosed, the GSA is rumored to be paying in the low $50s per square foot for a 20-year term at the tower.

Coupled with Condé Nast's 1 million-square-foot, $2 billion lease to become the 3 million-square-foot 1 World Trade Center's anchor tenant, the deal vaults 1 World Trade Center past the crucial 50 percent-leased threshold. And in addition to Condé Nast, GSA formally joins Chinese real estate investment firm Beijing Vantone (200,000 square feet) among the tower's first three tenants.