Santorini is what remains of a massive volcanic eruption that occurred around 3,600 years ago. This catastrophic event, one of the largest in recorded history, caused the center of the island to collapse, forming the large, water-filled caldera and crescent shape that makes Santorini so famous today.

Amsterdam is famous for its intricate canal system, but an interesting fact is that it has more canals than Venice and more bridges than Paris. The city is also built on millions of wooden poles, which were necessary to provide a stable foundation on the soft, marshy ground below sea level.

Málaga is the birthplace of one of the most influential artists of the 20th century, Pablo Picasso. The city honors its famous son with the Museo Picasso Málaga, which houses an extensive collection of his works, and the Fundación Picasso Museo Casa Natal (Picasso's Birthplace Museum), where visitors can see the home he was born in and spent his early years.

London is officially a forest. While it may seem like a sprawling concrete jungle, the city has a tree canopy of 21%, which means it meets the United Nations' official definition of a forest. It's home to millions of trees and a surprising number of green spaces, including parks, gardens, and woodlands.

While Ibiza is famous for its vibrant nightlife and electronic dance music scene, a less known fact is that a significant portion of the island is a UNESCO World Heritage Site. This includes not just its ancient walled city, but also its unique and biodiverse marine ecosystems, particularly the extensive meadows of Posidonia oceanica, a type of seagrass that helps keep the surrounding waters crystal clear.

Croatia was part of the six republics that formed the dissolved Yugoslavia and is home to the world's smallest town, Hum. Located in the heart of the Istrian Peninsula, this tiny walled town has a population that fluctuates between 20 and 30 residents. Despite its size, Hum has a rich history and even has its own mayor and a unique medieval ritual where residents elect their community leader each year by carving votes into a wooden stick.

Croatia was also part of the six republics that formed the dissolved Yugoslavia. The Bay of Kotor in Montenegro is often referred to as Europe's southernmost fjord, but it's actually a submerged river canyon. Its dramatic, steep cliffs that plunge into the water give it a fjord-like appearance, but it was formed by river erosion rather than glacial activity. This unique geological formation, surrounded by medieval towns like Kotor, Perast, and Risan, makes it a stunning and unforgettable landscape.

The name "Riyadh" is derived from the Arabic word "Rawdah," which means "gardens" or "meadows." This is a nod to the fact that the city was historically a fertile area with natural oases and lush spots, serving as a welcome respite for travelers crossing the Arabian Peninsula.