Finally, the pitter patter of feet at 510 Madison Avenue won't just be coming from the contractors. 

Senator Investment Group has signed an 11-year lease for 11,500 square feet, a source familiar with the deal told The Observer. The hedge funders will take the entire 28th floor of the 30-story building, which otherwise sits completely empty. 

The starting rent was "north of $100," the source said, which puts it in line with the prime rents that prime buildings were fetching when it was built. There's a lot of activity at the building right now, according to the insider, who added a number of leases are upcoming. 

Mort Zuckerman's Boston Properties purchased the building for around $275 million from Harry Macklowe in September after months of agonizing by the beleaguered owner. The building is a relic, distant not in time but in attitude, with a pool, health club and all-glass design. It has since survived an electrical fire and the implosion of an empire, but Boston Properties plans to spend $15 million to finish the construction. 

Jason Lund of Cushman & Wakefield represented the tenant. Paul Amrich of CB Richard Ellis represented the landlord. 

lkusisto@observer.com