AT&T Stadium is undergoing some changes after all -- but its got nothing to do with a tarp blocking the sun -- 'cause a massive piece of roof fell ahead of the Texans-Cowboys Monday Night Football game.
It happened on Monday afternoon as the retractable domed roof was opening a couple of hours before kickoff in Arlington, TX ... so fans could enjoy the night sky for the first time in two years.
Unfortunately, while the roof was opening, a humongous piece from the roof fell .