To place the eastern windows back into their original locations, the Restoration Team searched for architectural evidence that could be used to match the ca. 1812 windows' rough openings with the reused Madison-era window frames.  During the investigation it was discovered that nail holes found on the bottom of the window headers, which survived for every ca. 1812 window on the east elevation, could be matched to nail holes found on the top of the window frames.  These nail holes were made by ca. 1812 nails which secured L-shaped, wrought-iron braces that originally held the window frame in the rough opening.  Once the nail holes in the header were aligned with nail holes found at the top of the window frame, the Team knew for sure that they had a match.  Using this method, all of the ca. 1812 windows that had been reused by the duPonts were returned to their Madison-era locations.