The world is full of structural man-made marvels. Just go to any city or landmark and you’ll see a plethora of architecture that’s as fascinating as it is impressive.

Sometimes, though, the origin of these epic creations is shrouded in mystery. No one is quite sure who the original builders were. This adds an element of secrecy that excites historians and visitors alike.

On the island of Euboea, Greece, there are 23 mysterious megalithic structures, known as dragon houses, hidden deep in the mountains. Their existence has left experts puzzled and tourists fascinated, and when you see them for yourself, you’ll see exactly why…

Watch the video for more about the Dragon Houses!