1) The Serengeti National Park, located in Tanzania and extending into Kenya, is renowned for its vast savannahs, diverse wildlife, and the annual wildebeest migration. It is a UNESCO World Heritage site and a popular destination for safari enthusiasts and nature lovers.

2) The Great Barrier Reef, situated off the coast of Queensland, Australia, is the largest coral reef system in the world. It stretches over 2,300 kilometers (1,400 miles) and is home to a diverse array of marine life, making it a popular destination for diving and snorkeling.

3) The abolition of slavery in the United States was officially proclaimed with the ratification of the 13th Amendment to the Constitution in 1865.

4) The word "flower" contains two vowels: O and E.