Bill Ackman’s Pershing Square Capital Management and the Pershing Square Foundation have finally signed a lease for 67,000 square feet encompassing the entire top ninth and tenth floors of 787 Eleventh Ave. Ackman is also a partner in its redevelopment with the Georgetown Company.

These newly created floors will be clad in glass and set back to create a terrace that will wrap around the entire ninth floor. A new 11th-floor roof garden will also become an amenity space for all the office tenants as will the tennis court that ace Ackman desired.

To get the extra space, the design by Rafael Viñoly Architects raises the roof of the eighth floor and demolishes the southern side of the seventh floor to become a 39,693-square-foot mezzanine looking out over the full 57,749-square-foot sixth floor.

The office floors’ windows are also being enlarged to provide sweeping floor-to-ceiling views over DeWitt Clinton Park and the Hudson River to the Intrepid. The two connected sixth and seventh floors and the entire full eighth floor are available with an asking rent in the mid-$70s and occupancy in 2017. A CBRE team led by Mary Ann Tighe is handling the leasing.

“We felt creating that drama and that unique situation on the sixth and seventh floors makes it special,” said Georgetown’s chief executive, Adam Flatto.

The rent for Pershing Square was not revealed.

Georgetown also secured a $349.5 million construction loan from Blackstone Real Estate Debt Strategies, thus replacing its $200 million acquisition loan from JPMorgan Investment Management.