1) The highest mountain in Africa is Mount Kilimanjaro, standing at 19,341 feet (5,895 meters) tall.

2) 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.

3) The discovery of the Americas by Christopher Columbus in 1492 opened up new trade routes and had a profound impact on world history.

4) The Southern Ocean surrounds Antarctica and is the coldest and least-visited ocean.