The restoration project has unfolded like a detective story.

When Marion duPont Scott bequeathed the house to the National Trust for Historic Preservation in 1983, she asked that it be restored to its Madison-era appearance as a tribute to the nation's fourth president. But the process was problematic. Could a 55-room Gilded Age mansion be converted back to a 22-room Colonial home? How would preservationists know what was original to the site and what had been added in more than 180 years of additions and renovations?

In November 2001, the Paul Mellon estate gave Montpelier $750,000 to conduct investigations into the property's historic and architectural record. Archivists studied letters and documents from Madison and his contemporaries while architectural historians examined the building's walls, foundation, floors and ceilings, developing a computer database that allowed them to track where each nail had been placed. They found more than enough detailed information to move forward, officials say.

The sleuthing and the actual deconstruction work has revealed many previously hidden details. There had been 51 doorways in Madison's home, for example, and it turned out that the thrifty duPonts had recycled many of them, moving them elsewhere on the property, so now they can simply be moved back to where they were.

The original entrance was flanked by glass windows that could open and shut via hidden wall pockets, allowing cooling breezes to circulate through the house, but after the entry was enclosed by the duPonts, the wall pockets were painted over and sealed into place, and the early air-conditioning strategy was forgotten.

Researchers were baffled by a guest's reference to his stay in the "floral room," but the mystery was solved when a duPont closet was ripped out and the plaster was stripped away, revealing a colorful hand-painted picture of what appears to be a sassafras leaf. It was probably part of a frieze that ran around the room.

"It's just been a matter of finding where the pieces went, like putting a puzzle together," said Michael Quinn, president of the Montpelier Foundation.

-- Kirstin Downey

"Montpelier, Late Residence of Madison," an engraving by an unknown artist circa 1836. The Orange County, Va., mansion had 22 rooms, 51 doorways and a lost "floral room."A 2003 adaptation by Rick Moyer of the companion portraits of James and Dolley Madison by Allan Dordick after Gilbert Stuart's 1804 originals.