Architecture lease deal.

An international architecture and planning firm has signed a lease to snag a rare piece of creative office space at a downtown office building.

RTKL Associates Inc. has signed a 10-year lease to expand into 40,000 square feet of concourse-level space at the Bank of America Plaza.

The $10.5 million lease deal with landlord Trizec Properties Inc. allows the firm to nearly double the size of its Los Angeles office. RTKL has occupied 25,000 square feet of space on the building's concourse level since 1996.

"We like to be on one floor," said RTKL chairman Paul Jacob. "It's one big open space."

The large, open office area in the 333 S. Hope St. building is unique for a downtown office building, and this helped RTKL secure the space at a below-market rate, said David Kluth, executive managing director at Studley Inc., which represented RTKL in the deal.

The lease works out to about $263 per square-foot.

"It's well below market for Class A space," Kluth said. "The uniqueness of the space cut both ways; the prospects for concourse level creative type space aren't unlimited--especially in downtown L.A. Had this space been in a different market where the creative or entertainment industries may typically reside this space may have demanded a greater rental value."

Jacob said that the firm, which has had a presence in Los Angeles since 1986, needs the additional space at the 55-story building after adding over 50 employees to the Los Angeles office in the last two years. About 200 people will work in the expanded office.

"I think it's gratifying to us that after 20 years in L.A. we are participating in What we want to do as a finn which is affect the physical environment of the cities we occupy," Jacob said.

Studley executive managing director Josef Farrar also represented RTKL in the transaction. Trizec was represented in-house by John Barganski and Patrick Lacey.