D.C. Mayor Anthony A. Williams (D) said yesterday that the city will create a redevelopment authority to begin studying how to convert the Walter Reed Army Medical Center campus into the District's newest neighborhood.

The historic hospital between 16th Street and Georgia Avenue in upper Northwest is to close in 2011 as part of the federal base-closing process.

"We want to see this compound opened up and incorporated back into the fabric of our city," Williams said. "The opportunity to redevelop 113 acres in the heart of the city represents tremendous opportunities and, I think, tremendous challenges."

Before the hospital can be offered to the city, the Department of Defense must decide whether it will keep the land. It could also sell the land to the highest bidder or negotiate a sale or transfer to the District, said Del. Eleanor Holmes Norton (D-D.C.). Other federal departments also could request the land.

Communities affected by base closures often create local redevelopment authorities, city planning director Ellen McCarthy said. Those entities negotiate with the Pentagon on any sale or transfer of the property to the community.

Norton said that the District is right to start planning but that there is no guarantee the federal government will sell or give the land to the District.

"Nothing is automatic," Norton said. "The process is not designed to help the District of Columbia.''

The historic Army hospital was selected for closure earlier this year by the Base Realignment and Closure Commission. City officials said the commission's recommendations took effect Tuesday.

Stanley Jackson, the deputy mayor for planning and economic development, said he wants some sort of mixed-use project that would create employment once Walter Reed and its 1,300 jobs move to Bethesda. The Pentagon plans to expand what is now the National Naval Medical Center to create a "world-class flagship facility" on the Bethesda campus.

Williams said the new redevelopment authority will prepare a plan that takes into account the desires of the neighborhoods that border the hospital. He said that the authority's leadership will include residents and that its proposals will be publicly debated.

"The community is going to be engaged slice after slice, step after step,'' Williams said.

Some want to go further. D.C. Council member Adrian M. Fenty (D-Ward 4), who represents the area around Walter Reed, said he wants the new authority to be headed chiefly by community residents.

Fenty said neighbors want a plan that will preserve open space that connects with nearby Rock Creek Park, single-family housing and neighborhood retail shops along Georgia Avenue.

Williams said he wants the plan completed by the end of 2006, which is also the end of his term as mayor. By starting the planning process now, Williams said, he hopes to avoid the problems other cities have run into while converting military bases.

He studied the experience of San Francisco when it was forced to close several facilities in the 1990s.

The mayor said the closure and redevelopment of San Francisco's Presidio Army base is an example of how to do it right. The base, which has stunning vistas overlooking the Golden Gate Bridge, has been converted into a national recreation center with residential neighborhoods and office space.

He cited the conversion of San Francisco's Treasure Island Naval Station, an effort that has been mired in bureaucratic inertia for years, as the way to do it wrong.

"We've got a great example of how it should be done and a not-so-great example,'' Williams said. "We want to take the better example.''

Staff writer Debbi Wilgoren contributed to this report.

Williams wants a plan for the hospital site by the end of 2006.