1) The fall of the Berlin Wall in 1989 symbolized the end of the Cold War and the reunification of East and West Germany.

2) Kim Kardashian West is an American media personality, businesswoman, and socialite. She gained fame through reality television show "Keeping Up with the Kardashians" and has built a successful brand empire encompassing fashion, beauty, and other ventures.

3) The Mongol Empire, under the leadership of Genghis Khan, became the largest contiguous empire in history, spanning from Asia to Europe.

4) The Mona Lisa, painted by Leonardo da Vinci, is one of the most famous and valuable artworks in the world.