1) The Sahara Desert, located in North Africa, is the largest hot desert in the world, covering an area of about 9.2 million square kilometers (3.6 million square miles). It is characterized by vast stretches of sand dunes, rocky plateaus, and extreme temperatures.

2) The Industrial Revolution, which began in the 18th century, brought about significant changes in agriculture, manufacturing, mining, and transportation.

3) The game of baseball, often referred to as "America's pastime," is played between two teams of nine players and has a rich history dating back to the 18th century.

4) The construction of the Great Wall of China began in the 7th century BC and was completed over several centuries, spanning thousands of miles.