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

2) The most-watched TV series finale in the United States was "MAS*H," with an estimated 105 million viewers.

3) The ancient city of Athens, Greece, is often considered the birthplace of democracy, where citizens had a say in the decision-making process.

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