The Vehicle (originally Vertical) Assembly Building, or VAB, at NASA's Kennedy Space Center (KSC) was first used to assemble the massive American Saturn V launch vehicles beginning in 1967. At 3,664,883 cubic meters it is one of the largest buildings in the world by volume. The building is at Launch Complex 39 at KSC, halfway between Jacksonville and Miami, and due east of Orlando on Merritt Island on the Atlantic coast of Florida. The VAB is the largest single-story building in the world, was the tallest building (160.3 m) in Florida until 1974, and is still the tallest building in the United States outside an urban area.

The VAB, which was completed in 1966, was originally built to allow for the vertical assembly of the Saturn V rocket for the Apollo program and referred to as the "Vertical Assembly Building". In anticipation of post-Saturn projects such as the Space Shuttle program, it was renamed to the "Vehicle Assembly Building" in 1965, and was used for the shuttle's external fuel tanks and flight hardware, and to mate the Space Shuttle orbiters to their solid rocket boosters and external fuel tanks.