The Taj Mahal, India's iconic ivory-white marble mausoleum in Agra, is the second best UNESCO world heritage site in the world, according to a new survey.

With over 8 million visitors per year, the monument of love built by mughal emperor Shah Jahan in the memory of his beloved wife Mumtaz Mahal, is rated after Cambodia's Angkor Wat.

Conducted by online travel portal TripAdvisor, the survey lists the UNESCO Cultural and Natural heritage sites best rated by travellers around the globe.

"You can find hundreds of tours and experiences to visit this mesmerizing site, from a private tour with guide and visit at sunset or sunrise, to a visit including a home cooked meal at a local home in Agra," the travel portal said.

Best toured with a knowledgeable guide, Angkor Wat has in store fascinating facts about its building process as well as history.

"The best views are at dawn or dusk, when the crowds have gone and the lighting reveals its true majesty," Trip Advisor said.

Other popular heritage sites on the survey include the Great Wall of China built by Xu Da of Northern Qi Dynasty in 1368 AD. Machu Pichu in Peru in South America has bagged the fourth spot with a 5-day hike of the Inca Trail, the 15th century Inca citadel and much more on offer.

Iguazu National Park in Brazil, Italy's Sassi of Matera, Auschwitz Birkenau and historic Krakow in Poland, the old city of Jerusalem in Israel and the historic areas of Istanbul in Turkey have also made to the list.