Patent Office Roof: Pending

Enclosing the courtyard, officials said, would provide a year-round use for public and private events. It will be one of the largest social spaces in Washington.

From the beginning, the project has raised concerns among preservationists. Review of this project went as high as the Secretary of the Interior's office and included the State Preservation Office of D.C., the Commission of Fine Arts, the National Capitol Planning Commission and the Committee of 100 of the Federal City.

The Advisory Council on Historic Preservation staff report says the Smithsonian rejected most suggestions for changes in its plans for the courtyard and the canopy. In March, the Smithsonian decided to conclude its discussions with the ACHP.

Some critics of the renovation, said the ACHP letter, objected to the destruction of the courtyard's landscaping, an open garden that was accessible to the public. The Smithsonian took down several mature elm trees and uprooted the yard and is building an underground auditorium.

Preservation groups also objected to the height of the canopy, its visibility from certain street corners and its initial lighting plan. "The idea expressed of a 'beacon' to draw people to the museum and enhance the adjoining neighborhood is not out of character with the monumental importance L'Enfant placed on the site as central to his plan for the city. However the building itself should serve as the beacon and should be lighted accordingly, rather than lighting the night sky, diverting attention from the historic building itself," said the ACHP.

Smithsonian officials also said they have lowered the height and altered the lighting.

Several preservation groups said the enclosure would have a negative impact on the building. "The design of the canopy, while exhilarating and innovative in its own right, overpowers the Greek Revival edifice in a way inappropriate to a building of this rarity," said the Interior Department report. It sided with the critics who do not want the canopy, but that conclusion isn't binding on the Smithsonian.

Foster has made some changes to the design in response to the critics -- for example, relieving the walls of the extra weight by attaching the glass roof to eight discrete pillars. But an ACHP staff report, prepared earlier this month, still had reservations, pointing out the "eight columns necessary to support the new roof introduce another series of elements out of character with the building facades that encompass the courtyard."

The Commission of Fine Arts approved the enclosure project in January, with some questions about the glazing. The National Capital Planning Commission has approved preliminary plans and will hold a full review as early as June.

All of the preservation oversight groups have asked the Smithsonian to reconstruct an exterior staircase that was torn down in 1936 so F Street could be widened. The Smithsonian has agreed to do so and include the cost in its fiscal 2007 request to Congress.

The original $38 million estimate for the canopy was based on a design estimate and moved to approximately $50 million as the design was finalized. "The euro has worked against us, the price of the materials changed and we had to make adjustments, suggested by the review panels, such as the lowering of the height," Burke said.