The study originated during a trip to Europe, where the couple stumbled upon a book about World Heritage Sites. Intrigued by UNESCO's classification criteria, they were struck by the rigid ...

These are the 25 countries which are home to the most significant cultural, historical and natural sites, according to UNESCO.

Locations deemed World Heritage sites are of "outstanding universal value to humanity" and should be "protected for future generations to appreciate and enjoy," according to Unesco. The ...