To discover how large the ca. 1797 door was the Restoration Team looked for evidence on the surviving ca. 1797 floor.  The floor had been entrapped under a duPont-era floor that was installed when the Madison-era wall between the North Passage and the Dining Room was removed to create a billiard room.  Because the Madison floor had been protected under the replacement floor for over a hundred years, the Restoration Team hoped that evidence of the Madison-era doors had survived.