You can’t believe everything you see on the internet, but every few months it delivers something that has people tearing their hair out as they try to figure it out. Remember the infamous white-gold, black-blue dress? Or the helicopter whose rotors don’t seem to be moving?

On April 29 Twitter user @QuickTempaa uploaded a video of a spiral staircase at the San Sorino Stadium in Milan. And the gigantic staircase seems to be spinning in the video (above).

It stumped the internet, for it seems physically impossible. And so it was, as the person who uploaded the video pointed out. the “spinning” of the staircase is just an optical illusion.

It is the movement of the people on the staircase that creates the illusion that it is spinning. If you focus on a particular spot on the staircase, you’ll be able to see it.

Several internet users, however, weren’t convinced.

They argued that the stairs were “circular escalators” and “deffo moving”, even when people who had visited the stadium in real life reiterated the truth: