Latham & Watkins LLP, one of the nation’s most profitable law firms, is leaving its flagship space at downtown’s U.S. Bank Tower for another Bunker Hill skyscraper.

Though Latham’s lease for multiple floors at the landmark 73-story U.S. Bank Tower expires in December 2009, the law firm will move out about a year early, according to a company spokesperson.

The firm will move to the KPMG Tower at Wells Fargo Center, 355 South Grand Ave., which like the U.S. Bank Tower is owned by Maguire Properties Inc. The lease deal has yet to be finalized.

“While both buildings provide superior office locations and facilities, the move is being considered to accommodate a complete renovation of our office space in order to create an enhanced work environment and client experience,” the firm said in a statement.

With news of the move coming amid reports that al Qaeda had planned to fly a plane into the U.S. Bank Tower the tallest high rise west of the Mississippi there has been speculation among downtown real estate brokers that terrorism concerns may have been at play.

However, officials at Maguire, Latham and the law firm’s broker strenuously denied that terrorism fears had anything to do with the move.

“It wasn’t that at all,” said Lynn Williams, executive vice president at Cushman & Wakefield Inc., who is representing Latham in the deal. “It was really about an opportunity to build new space to create this work environment and client experience that was so important to them.”

Robert Maguire, chairman and chief executive of Maguire Properties, said that the move will make the firm more efficient. “We can do it in a guaranteed time schedule that makes a ton of sense to Latham. It works extraordinarily well for them; they get a lot more efficiency,” he said.

One thing is certain: Latham is moving into about 300,000 square feet of space at an office plaza that already houses two powerhouse firms.

With Latham’s departure from U.S. Bank Tower, a huge block of space in the marquee building will be available for rent in 2008.

Maguire’s Peter Johnston, Pat McRoskey and Josh Wrobel are representing the company in-house on the deal. Latham is also being represented by Cushman & Wakefield’s Jeff Welch and Scott Gamber, an executive vice president at CB Richard Ellis.