13 historic monuments, puzzles which are still not solved

7. Petra, Jordan

Nestled at an altitude of 900 meters above sea level, this monumental site is hidden among the rocks. The craftsmen displayed incredible patience, carving out the breathtaking beauty of Petra.

As you journey through the cool canyon, you are rewarded with a stunning view of the facade adorned with columns and porticos—Al Khazneh, which means "Treasury" in Arabic.

It might have been a temple or perhaps a mausoleum. Yet, many mysteries remain, particularly regarding how the carvers accomplished their work. After all, they must have used scaffolding, but where could they have obtained it?