Now more than ever, people are eager to explore the world. Wanderlust has become the world's favorite indulgence, seeking new landscapes from every corner of the planet. There is, regrettably, a downside to rising number of tourists visiting the most beautiful places around the globe.

According to a report from Associated Press via ABC News, the massive influx of people in the UNESCO World Heritage Sites has resulted in a number of negative effects. Four places in particular bear the brunt of the damage and are now tagged "at risk" sites -- Machu Picchu in Peru, Omori in Japan, Lijiang in China and Mont-Saint Michel in France.

Machu Picchu is one of the world's famed destinations. Countless of tourists have treaded the path to this UNESCO World Heritage Site, embarking on a pilgrimage of a lifetime. The overwhelming travelers on the site has reached around 2,500 per day, way more than the 15th century retreat's expected capacity of about 800 people.

The swelling number is the root of a lot of problems expected to emerge in the Machu Picchu such as vehicle fumes and the endless foot traffic that could lead to a small-scale earthquake and the consequential collapse of the famed structures.

A report from Conde Nast Traveler revealed that both Peru and UNESCO have begun to take measures in protecting the famous site. Hoping to lessen the negative effects of tourism, tourists are required to keep to the three approved hiking routes available, and the number of visitors have been limited to 2,500 daily.

Another site that was recently added to the list of places in danger is the town of Omori in Japan. The quiet town boasts a defunct silver mine and very little infrastructure to cater to crowds. However, ABC News revealed that one year after it was inscribed as a World Heritage Site in 2007, a million tourists suddenly rushed in, "rupturing the quiet lifestyle of the unprepared community."

Lijiang is another such town: it was inscribed in 1997, developed to be one of China's top domestic tourist destinations and is now facing the risk of losing its local culture and ethnic roots to newcomers eager to profit from the tourist draw. Before being named a World Heritage Site, Lijiang welcomed 150,000 visitors annually. Last year, it had around 16 million.

The last destination in the list is Mont-Saint Michel, France. One of the first destinations named a World Heritage Site, the islet remains a huge draw as a pilgrimage destination from the back in the Middle Ages. However, it's not meant to hold huge numbers, especially the 2.8 million visitors it gets every year; Mont-Saint Michel is only 100 hectares with a resident population of 50 people.