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

2) The world's largest ocean, the Pacific Ocean, covers an area of approximately 63 million square miles.

3) The construction of the Great Wall of China began in the 7th century BC and was completed over several centuries, spanning thousands of miles.

4) The Atlantic Ocean is the second-largest ocean and is known for its strong ocean currents, including the Gulf Stream.