Hidden in plain sight are doors that were designed to blend seamlessly into the décor and lead to secret passageways. These passageways were designed to help George Vanderbilt's guests and Biltmore staff navigate efficiently and privately from common areas to other rooms in the house.

While the Biltmore House in Asheville, North Carolina, doesn't have "Indiana Jones" style revolving walls or trapdoors, it is famous for its hidden "discreet" doors designed to maintain the house's perfect architectural symmetry. In the grand Library, there are two "secret" doors: one is hidden behind a tapestry over the fireplace which leads to the guest bedrooms on the second floor, and another is hidden in the wood paneling that leads to the Library Den. In the Breakfast Room, there is a door camouflaged into the wall (below a Renoir painting) that leads directly to the Butler’s Pantry and a dumbwaiter, allowing the staff to deliver hot food without walking through the public hallways. There is also a "hidden" door in the Billiard Room that allowed gentlemen to retire to the Smoking Room without being seen. These weren't built for "spy movies" but for social etiquette—the goal was to hide the "gears" of the house (the servants) so that the Vanderbilt family and their guests could live in an environment of effortless luxury where the work happened invisibly behind the scenes.