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) Antarctica is the coldest, driest, and windiest continent on Earth. It is also the highest, with an average elevation of about 7,545 feet (2,300 meters).

3) Oceans play a crucial role in regulating the Earth's climate by absorbing and storing large amounts of heat and carbon dioxide.

4) The English alphabet has five vowels: A, E, I, O, and U.