1) The world's tallest waterfall is Angel Falls in Venezuela, with a height of about 3,212 feet (979 meters).

2) The study of fossils is called paleontology, and it helps us understand the history of life on Earth and the process of evolution.

3) Celtic mythology encompasses the folklore and legends of the Celtic peoples across Europe, particularly in regions like Ireland, Scotland, and Wales. It features deities like Morrigan, Cernunnos, and Brigid, and delves into themes of nature, magic, and the heroic exploits of legendary figures like Cu Chulainn.

4) The Taj Mahal, located in Agra, India, is an iconic mausoleum recognized as a UNESCO World Heritage site. It was built in the 17th century by Emperor Shah Jahan as a testament to his love for his wife and stands as a masterpiece of Mughal architecture and a symbol of India's cultural heritage.