1) The Nile River, spanning approximately 6,650 kilometers (4,130 miles), is the longest river in the world. It flows through eleven countries in northeastern Africa, supporting various civilizations throughout history and serving as a vital source of water and transportation.

2) The world's largest volcano, Mauna Loa in Hawaii, is also one of the most active. It stands over 13,000 feet (4,000 meters) above sea level.

3) The assassination of Archduke Franz Ferdinand of Austria in 1914 triggered the start of World War I.

4) 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.