The Vehicle Assembly Building at NASA's Kennedy Space Center is so large that rain clouds form inside it.
VAB, for short, was used from 1968 to 2011 to build and store American space vehicles. By volume it is one of the largest buildings in the world, at 3,664,883 cubic meters. Additionally, it is the largest single story building in the world, and until 1974 was the tallest building in Florida.
Today, it is the tallest building in the US outside of urbanized cities like New York and Cincinnati. The VAB completed its construction in 1966 and was first used to build the Saturn V rocket for the Apollo program.
After that it was used for housing Space Shuttle fuel tanks and other flight hardware, and served as a place where Space Shuttle orbiters were attached to rocket boosters. At 526 feet tall, 716 feet long, and 518 feet wide, it covers 8 acres of land. At such a size, on very humid days the building has its own weather, with rain clouds forming below the ceiling.
The building has a moisture reduction system to mitigate this problem, though. What’s odd is that the building is made to withstand hurricanes and tropical storms, but weather still appears inside it.