Which architectural support pushes from the outside to help hold a heavy wall?

• A. Buttress
• B. Flying buttress
• C. Arch
• D. Pier

Answer: (B)

External supports are used to transfer the outward push from heavy walls and vaults to a solid footing away from the wall itself. The flying buttress does this in a distinctive way: a slender arch projects from the wall and connects to a separate exterior pillar, so the thrust is sent across the air to that external support and down into the ground. This lets the wall remain tall and thin while carrying a lot of weight, which is a hallmark of Gothic architecture. A regular buttress sits against the wall but doesn’t involve that arched external connection; an arch is a curved span within or above openings, and a pier is a vertical support, neither of which specifically describe redirecting thrust to an outside support.