A trap door in the Pompeian Room of the 16th-century Villa Farnesina in Rome revealed previously unknown frescoes by the painter Carlo Maratta and two students.Credit...Filippo Monteforte/Agence ...

Or is it just the internet messing with us again? I saw some Reddit comments claiming that it helps prevent a clever dog from opening the door and another claimed it protects the knob from getting too ...