1) In Greek mythology, the Trojan War is a legendary conflict between the city of Troy and the Greeks, sparked by the abduction of Helen of Troy. It is immortalized in Homer's epic poems, the Iliad and the Odyssey, and features famous heroes like Achilles, Hector, and Odysseus.

2) 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).

3) The Dead Sea, located between Jordan and Israel, is the lowest point on Earth's surface. Its saltwater is so dense that people can easily float on its surface.

4) The assassination of Archduke Franz Ferdinand of Austria in 1914 triggered the start of World War I.