The northern wall of the ca. 1764 South Passage is one of the most altered walls in the Mansion. Both the Madisons and the duPonts made major changes to the wall's doorways, and during the duPont ownership it was even divided by a new partition. How did the Restoration Team at Montpelier determine where the ca. 1764 and ca. 1812 doors were located after all of these changes? Essentially the process involved looking for irregularities on the surviving brickwork to find evidence of the changes.