The Zagreb branch is the original — a hands-on, photo-friendly museum of optical illusions, distorted rooms, and visual puzzles that opened in 2015 and has since franchised into dozens of cities around the world. Inside: the ubiquitous Ames room (people appear to grow and shrink), a vortex tunnel, a head-on-a-platter table, anti-gravity rooms.
It is more a slightly grown-up theme park than a serious museum, and you spend most of your time taking photos. Children love it; sceptical adults usually capitulate after the first or second illusion. Allow 45 minutes to an hour. Tickets are cheaper online than at the door.