1) The Amazon Rainforest, located in South America, is the largest tropical rainforest in the world, covering an area of approximately 5.5 million square kilometers (2.1 million square miles). It is known for its exceptional biodiversity and plays a crucial role in the global ecosystem.

2) The ozone layer, located in the Earth's stratosphere, protects us from harmful ultraviolet (UV) radiation.

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

4) The deepest part of the ocean is the Mariana Trench, reaching a depth of about 36,070 feet (10,994 meters).