Paradox Museum Stockholm is an indoor exhibition at Hötorget, with more than 70 interactive installations built around perspective and optical illusions. Visitors walk through the exhibits and try the effects themselves. The Paradox Tunnel spins around you, while the upside-down room turns a living room’s floor and ceiling around. Other installations include an infinity room, a camouflage room and a kaleidoscope. Visit Sweden also describes spinning walls, a self-playing piano and a room where children appear taller than adults.

Tickets start at SEK 195 (about US$19.0) for children and SEK 249 (about US$24.2) for adults. The museum is open daily from 10:00 to 19:00, with last entry 60 minutes before closing. Opening hours may be longer during school holidays and public holidays, so check the online booking page for current times. The visit takes about 60 to 80 minutes. All ages are welcome, but visitors under 16 must be accompanied by an adult. Tickets can be booked online or bought at the museum.

Photos and videos are allowed. Food and drink are not allowed in the exhibition area. Some displays use lighting effects that may affect people with light sensitivity; staff can advise on arrival. There are no fixed seats during the walk-through, but visitors who need a rest can speak to staff. QR codes at the exhibits link to information about their history and the science behind each paradox; there is no audio guide. The address is Sergelgatan 20. From Hötorget station, take the south exit towards Sergelgatan.