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

2) The concept of self-driving cars, or autonomous vehicles, is being actively developed by companies such as Tesla, Google (Waymo), and Uber.

3) In Aztec mythology, Quetzalcoatl is a prominent deity often depicted as a feathered serpent. He is associated with creation, fertility, and wind, and is considered a cultural hero and patron of priests and rulers. The arrival of Spanish conquistadors was interpreted by some as the return of Quetzalcoatl.

4) The Tour de France, first held in 1903, is one of the most prestigious and grueling cycling races, covering over 3,500 kilometers (2,200 miles) in three weeks.