When it was built in the 1960's the Vertical Assembly Building at the Kennedy Space Center was the largest building in the world by volume. It has a sophisticated climate control system, if it didn't it would cloud up an rain inside. There are four massive assembly spaces, and an open central core. Before the Shuttle program, tours were allowed inside the building, I have been there. I lived across the river from it, went to half of high school across the river from it. Have you seen it in person?