1) The ocean covers about 71% of the Earth's surface and contains roughly 97% of the planet's water.

2) 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.

3) The Machu Picchu archaeological site, located in Peru, is an ancient Incan citadel situated high in the Andes Mountains. It is recognized as a UNESCO World Heritage site and attracts visitors from around the world who come to marvel at its remarkable architecture and scenic surroundings.

4) In Norse mythology, the World Tree, known as Yggdrasil, is a massive ash tree that connects the nine realms of existence. It is considered the center of the cosmos and serves as a conduit between different realms, including Asgard (realm of the gods), Midgard (realm of humans), and Helheim (realm of the dead).