1) The European Union (EU) is a supranational organization comprising 27 member states that cooperate on various issues, including trade, economic integration, and common policies, while preserving individual national sovereignty.

2) The world's largest desert is the Antarctic Desert, covering around 5.5 million square miles.

3) The Great Wall of China is not visible from space without aid, contrary to popular belief.

4) The concept of sovereignty refers to the supreme authority and power of a state to govern itself, make decisions, and control its own territory without interference from external forces.