No one close to the deal is talking. That includes building owner Equity Office Properties and brokerage firms CB Richard Ellis, which represented EOP, and Cushman & Wakefield, which spoke for Dechert.

But industry sources estimate the value of the lease at $300 million. That includes rents that range from $85 to $95 per foot on floors 25 to 30 and up to $101 on the 31st floor. The deal, which spans a 15-year term, also includes nine months of free rent.

EOP's New York leasing vice president Michael Berman worked with CBRE's Robert Alexander, Robert Stillman and Zachary Freemen to nail down the details. Mitchell Konsker, Matthew Astrachan, Paul Glickman and Robert Gallucci sat on the other side of the table. EOP's legal representation was Paul, Hastings, Janofsky & Walker LLP.

It's been a period of expansive growth for law firms around town, and Dechert's deal comes on the heels of a variety of major agreements. These include Darby & Darby's 80,000 sf at 7 World Trade Center and Hoskin & Harcourt; Covington & Burling; and Seyfarth Shaw, all of which signed for a total of 320,000 sf in the New York Times Building.

"The activity among law firms is driven by space consolidation and expansion, which is just the nature of a healthy economy," says Steven Durels, executive vice president of SL Green Realty Corp. Durels also signed a law firm recently, albeit to a smaller deal, at 100 Park Ave. Fox Rothschild LLP signed a 10-year lease expansion and renewal for 30,578 sf there. "All of them seem to be pushing for higher profiles. It's an image-conscious business and the quality of the space is always part of their calling card."