1) The highest-grossing concert tour of all time is U2's "360° Tour," which earned over $735 million in ticket sales.

2) Michael Jackson's album "Thriller" is the best-selling album of all time, with estimated sales of over 66 million copies worldwide.

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 World Wide Web, developed by Tim Berners-Lee in 1989, revolutionized the way information is accessed and shared on the internet.