1) The word "book" contains two vowels: O and O.

2) The world's oldest university, Al-Qarawiyyin, was founded in 859 AD and is located in Fez, Morocco.

3) The world's largest desert is the Antarctic Desert, covering around 5.5 million square miles.

4) The Plitvice Lakes National Park, situated in Croatia, is a stunning natural wonder known for its cascading lakes, waterfalls, and vibrant turquoise-colored waters. It is a UNESCO World Heritage site and attracts visitors who come to explore its picturesque trails and scenery.