Built in the 1600s, this building in Agra, India, is a testament to undying love. This white marble tomb built for Emperor Shah Jahan’s deceased wife is a must-see for everyone. In 1983, it was named a UNESCO World Heritage site, and also has been named one of the New Seven Wonders of the World. The Taj sees between two and four million tourists annually, so there have been recent restrictions on tourism in an effort to help protect the site. However, the greatest threat is the air pollution that is destroying the marble.