The Eiffel tower is one of the biggest landmarks in the world and people flock to it every year, just to get a picture beside it.

But something that many do not know is that there is a secret apartment hidden inside the tower that nobody ever uses.

When the man himself, Gustave Eiffel built the tower in 1889, he built himself a secret get-away on the third floor. 

The small apartment is filled with wooden furniture and colourful wallpaper, as well as a grand piano. The designer even stashed the latest scientific equipment he found when he was out and about in Paris at the time. 

But you won't get to see this apartment anytime soon. Back when Parisan high society found out about Gustave's hide-away, they began begging him to rent it out.

He wouldn't let anyone inside it though, and even to this day – 92 years after his death – the tradition continues with the apartment only open once in a blue moon for public viewing.