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

2) The Federal Reserve System, often referred to as the Fed, is the central banking system of the United States.

3) Serena Williams is an American professional tennis player widely regarded as one of the greatest athletes in the sport. She has won numerous Grand Slam titles and Olympic gold medals and has become an influential figure both on and off the tennis court.

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