The Transportation Department headquarters will undergo a renovation costing more than $200 million after the department moves out in 2007, the building's owner said.

The building at 400 Seventh Street SW, which has 1.4 million square feet of office space, has been the department's headquarters for more than 30 years. In 2001, the General Services Administration, the federal government's real estate agency, recommended that the department move its 5,500 employees from the building to an 11-acre complex that is being built at the Southeast Federal Center.

The planned renovation would be one of several projects to upgrade Southwest, with its cluster of government tenants and moderately priced properties. JBG Cos. of Chevy Chase is redeveloping L'Enfant Plaza. Last year, Republic Properties Corp., a District developer, began construction of an office building. It is part of its Portals project, which is to have 3 million square feet of office, retail and hotel space by 2010.

After the Transportation Department leaves in 2007, David Nassif Associates, a District firm that has owned the building since its construction began in 1966, plans to renovate it.

"We're fully prepared to begin demolition of parts of the building after the last box leaves," said Timothy D. Jaroch, managing general partner of Nassif Associates. The limited partnership plans to look for tenants from government agencies and the private sector he said.

"We are not designing something that is not going to fit," Jaroch said.

The planned renovation is a necessary change to keep up with the standards of tenants, said David Varner, principal at SmithGroup Inc., the architecture firm hired to redesign the building.

Major renovations are to include an improved security system. The building now has a courtyard with four entrances. Under the planned design, the building would have a single entrance with a main security checkpoint.

"Everyone loves the daylight, the transparency and the freedom, but we have to provide some control," Varner said.

The renovated building is to have 1.5 million square feet of office space for about 7,000 employees.

Va. County Sells More Land

The federal government has bought more land in Prince William County.

The Architect of the Capitol paid T-Rex Capital LLC of New York $63 million for a 335,662-square-foot facility in the 116-acre office park called Innovation at Prince William. The architect already leases part of the facility, which is shrouded by trees and secured by barricades.

The agency is to remain on the property, where it stores records. Amtrak also leases space in the building, and its technology workers are to remain.

The sale came a month after the county sold 15 acres in the Innovation park to the General Services Administration for $2.6 million. A 199,110-square-foot facility will be constructed and leased to the FBI.

"It's quite obvious that the federal government has discovered Prince William," said Sean T. Connaughton, chairman of the Board of County Supervisors.

In November 2002, T-Rex bought the building and most of the land from Lockheed Martin Corp. for $22 million.

"It shows the value of commercial property in Prince William. It's really escalating," Connaughton said. He described the sale as one of the biggest in the county's history.

The property, built in 1984 as offices and a data center for International Business Machines Corp., was later sold to Lockheed Martin, which used the building for acoustic laboratories and office space before consolidating all its employees in its buildings across the street.

The Architect of the Capitol is responsible for the maintenance, operation and preservation of government buildings including the Capitol, congressional offices and the Supreme Court building.

Closings

* Anacostia Gateway LLC is to start construction tomorrow on a three-story, 63,000-square-foot office building at Martin Luther King Jr. Ave. SE and Good Hope Road, billed as the first new office project in the District's Anacostia neighborhood in 15 years. The $19 million project is to include 14,000 square feet of retail space, 49,000 square feet of office space, and 112 parking spaces. Construction will take 12 to 15 months, said Peggy Armstrong, spokeswoman for the National Capital Revitalization Corp.

* Lerner Enterprises, a North Bethesda developer, is to begin construction of a 10-story, 190,000-square-foot building at 20 M Street SE, next to the Navy Yard Metro station. Construction is scheduled for completion in summer 2007. The building is to include such features as fueling stations for battery-powered automobiles, bicycle parking and plumbing fixtures designed for reduced-water consumption.

* JBS Ventures LLC bought the Hotel Monticello at 1075 Thomas Jefferson St NW in Georgetown from Marbury Place LLC for an undisclosed sum. The sale closed June 21. Molinaro Koger, a hotel real estate brokerage, negotiated the deal.

Staff writers Jenalia Moreno and Nikita Stewart contributed to this report. Dana Hedgpeth, the regular From the Ground Up columnist, is away. In her absence, please send news about commercial real estate to business@washpost.com.

Above, the Transportation Department headquarters on Seventh Street SW. Below, a designer's concept of what it might look like after planned renovation. The department is leaving the building in 2007.