1) 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.

2) The highest mountain in Africa is Mount Kilimanjaro, standing at 19,341 feet (5,895 meters) tall.

3) Coffee is one of the most widely consumed beverages in the world, made from the roasted seeds of the Coffea plant. It is known for its stimulating effects due to its caffeine content and is enjoyed in various forms, including espresso, cappuccino, and latte. The cultivation and preparation of coffee have evolved into an art form, with different regions and methods producing unique flavors and profiles, offering a diverse range of experiences for coffee lovers.

4) The invention of the transistor by Bell Laboratories in 1947 revolutionized electronics and paved the way for the development of smaller, more efficient electronic devices.