Montgomery County officials have reached an agreement with Discovery Communications Inc. -- the international multimedia company -- to build a $150 million world headquarters in Silver Spring, bringing more than a thousand jobs and the potential for a distinctive new high-rise to the struggling downtown.

The deal is scheduled to be announced today on a four-acre site at Georgia Avenue and Colesville Road, in the heart of the business district, officials said. It follows state and county promises to provide Discovery Communications with $10 million in tax credits, grants and loans.

"This is a grand slam for Silver Spring. It will give Silver Spring a new identity," said Montgomery County Executive Douglas M. Duncan (D), who said he hoped Discovery's relocation would attract other media production companies to the location.

Downtown Silver Spring could be on the cusp of a revival after decades of decline. In addition to today's announcement, Montgomery officials this year approved plans for a $321 million revitalization project designed to create a new "downtown" consisting largely of stores, restaurants, a hotel and entertainment venues just across Georgia Avenue from the Discovery site. The plans also will bring the prestigious American Film Institute to the art deco Silver Theatre, which will be restored.

Discovery officials said AFI's presence gave them an added reason to select Silver Spring over other sites -- including the District and Northern Virginia -- that were considered during an 18-month search. With AFI and Discovery Communications across the street from each other, officials yesterday already were boasting about what they called the area's potential to become a major media center -- the "Burbank of the East Coast."

The company needed new office space to consolidate their operations. Currently, the company known best for creating the Discovery Channel has 800 employees scattered in four different buildings in downtown Bethesda. The company projects it will employ more than 1,100 people locally -- in addition to more than 3,000 others worldwide -- by the time the new headquarters opens, possibly within three years.

County officials said that the headquarters would hold about 500,000 square feet of office space and that some company officials are interested in building a distinctive office tower that would stand taller than any other building in downtown Silver Spring.

"They want something that will stand head and shoulders above everybody else," one county official said. "They want to stand out."

But Judith McHale, Discovery's president and chief operating officer, said that design has not yet been finalized and that the building could be a high-rise or a collection of smaller buildings. McHale said the company wants to create a "campus-like" atmosphere that could include a park.

McHale said Silver Spring was an attractive location for a variety of reasons. Its proximity to the current offices in Bethesda meant that employees would not be dislocated by the move. In addition, the site is near a major transportation hub, and it is large enough to provide for flexibility in design and enough space for the rapidly growing company to continue growing.

"We plan to be a major part of Silver Spring's revitalization," McHale said. "With AFI also moving in, it was a real opportunity for us."

The two organizations are currently discussing the possibility of creating joint programming in the area, officials said.

The new headquarters will be built on a site that once was earmarked for the ill-fated Silver Triangle Mall, a project proposed by developer Lloyd Moore in the late 1980s. The Silver Triangle was the first in a series of doomed redevelopment plans for downtown Silver Spring. Moore, who still owns the land, will develop the Discovery headquarters.

"I think it bodes really well for Silver Spring," Moore said yesterday. "This is just what so many of us have worked for and dreamed of for a very long time."