What are the mysterious facts in the world?

Here are some mysterious facts in the world which I want to share..
The shortest river in the world is Omla river, in Europe . It is only 30 meters.
2. The purpose behind Great Wall of China was not particularly to keep the Huns out. They could easily find places along the wall that they could climb using ladders. However, they could not get their horses across, without which they were not very effective warriors.
3. The world's largest cave chamber is Lubang Nasib Bagus in Sarawak , Malaysia. It is 2,300 ft. (701 m) long and 1,480 ft. (451 m) wide and at least 230 ft (70 m) high.
4. The famous Eiffel Tower in Paris was built as the entrances point for the 1880 World Fair. It is one of the most visited monument in the world.
5. Gaum doesn't have any natural sand , but rather coral, the island nation makes its asphalt using a mix of ground coral and oil rather than importing sand from abroad.
6. The Millau Bridge in France is the world's tallest bridge and France's tallest structure. At its highest point, it stands 343 m (1,125 ft) above the ground.
7. Saudi Arabia is the only land where there are no any rivers . Most of their water comes from desalination plants or underground reservoirs.
8. The Roman name for this place was Silva Nigra , the German name is Schwarzwald . The rest of the world remember it as Black Forest in Bavaria, mostly while ordering dessert.
9. Hindu Kush was the name given by the Persian to a mountain pass where numerous Indian slaves perished during the bitter winter.
10. The Persian cat is one of the world's oldest breeds. They originated in the high platform of the Iran where their long silky fur protected them from the cold .
11. The largest religious building ever built is Angkorwat , now in Combodia, enclosing 500 acres. It was built to honour the Hindu god Vishnu by the Khmer king Suryararman 2 between 1113 and 1150.
12. There are an artificial palm- shaped island in Dubai that can be seen from other space.