1) The Appalachian Mountains, running along the eastern coast of the United States, are one of the oldest mountain ranges in the world.

2) The coldest known temperature in the universe was achieved in a laboratory in 2019, reaching a fraction of a degree above absolute zero (-273.15 degrees Celsius).

3) The French Revolution, which began in 1789, marked a major turning point in European history, leading to the overthrow of the monarchy and the rise of republicanism.

4) The world's most expensive car is the Bugatti La Voiture Noire, which sold for over $18 million.