The Museum of Illusions in Zagreb has in reality grown into the world's biggest chain of private museums, offering fun as well education as it explores different perspectives in the human mind.
The museum displays a number of optical illusions such as water flowing uphill in defiance of gravity, a maze of mirrors, or climbing the ceiling.
"The illusions are entertaining and brilliant reminders that our perception of the world is sometimes just a perception" the museum says.
The Museum of Illusions opened in 2015 after two years of preparations inspired by the "Brain Games" TV show on the National Geographic channel.
"It was an idea about exploring the human mind in a different way," said Roko Zivkovic, the museum's owner and founder.
The museum has now became one of the most visited in the Croatian capital and has opened up franchises overseas due to the interest shown by foreign visitors.
"In these almost six years we turned into the biggest museum chain in the world with a presence in 30 places," Zivkovic said.
The locations include Paris, New York, Dubai, Toronto, Vienna and Shangai.
"Even during this pandemic period we managed to open eight museums elsewhere." Zivkovic said.
However, business was not entirely unaffected by the COVID-19 pandemic.
"Now we can receive here in Zagreb 20 or 30 visitors at a time, depending on the restrictions. The number of visitors fell as tourists and school groups at the moment do not come for a visit as before," Zivkovic said.
(Reporting by Antonio Bronic, writing by Igor Ilic, edited by Angus MacSwan)
