1) The Great Wall of China is a UNESCO World Heritage site and one of the most iconic man-made structures in the world. It stretches over 21,196 kilometers (13,171 miles) and was constructed to protect the Chinese empire from invasions during ancient times.

2) The ancient city of Pompeii was preserved under layers of volcanic ash after the eruption of Mount Vesuvius in 79 AD, providing valuable insights into Roman life.

3) Bats are the only mammals capable of sustained flight.

4) The world's largest species of shark, the whale shark, can reach lengths of up to 40 feet (12 meters) and weigh over 20 tons.