If you've ever lost the key to your house, you know how much trouble you have to go through to open the door again. But some doors in the world aren't meant to be opened at all because they're hiding some mysteries behind them! The famous Taj Mahal in India, for example, has a lot of doors that are always closed. Experts think that if someone opened these doors after they've been closed for so long, it'd release carbon monoxide, which could lead to the appearance of cracks in the minarets of the Taj Mahal. Find out more about these and other mysterious doors around the world!

Would you like to go on a tour of the world's most mysterious places? From the Bermuda Triangle to the Pyramids of Giza; from the Island of Dolls to Easter Island - there are so many places to discover and things to see! Near the city of Tiaret, 155 miles southwest of Algeria's capital, you can find 13 monuments shrouded in mystery, built between the 4th and 7th centuries CE. While moving down an ancient Aztec canal, you find this mysterious island with hundreds of abandoned dolls are hanging from trees. Are you getting the chills? Well, we're just getting started!