1) 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.

2) The first successful human heart transplant was performed by Dr. Christiaan Barnard in 1967.

3) The Andes, stretching along the western coast of South America, is the longest mountain range in the world, spanning over 4,300 miles (7,000 kilometers).

4) The Amazon rainforest produces more than 20% of the world's oxygen.