1) The concept of 3D printing, also known as additive manufacturing, was first introduced in the 1980s and has since revolutionized prototyping and small-scale production.

2) The Berlin Conference in 1884-1885 divided Africa among European powers and set the stage for the colonization of the continent.

3) The first car with air conditioning was released in 1939.

4) 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.