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

2) The national animal of Canada is the beaver.

3) The first modern Olympic marathon race was held at the 1896 Olympics in Athens and has since become one of the most iconic and challenging events in athletics.

4) The Great Barrier Reef in Australia is the largest coral reef system in the world and is visible from space.