While most people have heard of Angkor Wat, they don't realize that it's just one temple in a complex of more than 1,000.
The complex is actually a massive 700-year old city, with canals, temples, shrines and tombs spread over 154 square miles, deep in the lush jungles of northern Cambodia.
Take a look at these pictures to see why it topped the list of the world's must-see sites.
The Temples of Angkor are the architectural zenith of the Khmer Empire, which ruled from the 9th to the 13th centuries. For centuries, it was the Khmer Kingdom's capital, which at times ruled much of Southeast Asia, from modern-day Laos and Burma to Thailand and southern Vietnam.
More than two million tourists visited the site last year.
Angkor covers more than 154 square miles — in comparison, Manhattan only covers 33.
The Temples of Angkor are inside of the Angkor Archaeological Park, which is home to many other Khmer temples that were built between the ninth and 15th centuries.
It's also home to people, as some of the villages inside the park are inhabited, their income based on rice cultivation.
Each temple has intricate designs of various gods, but also of daily life. The Bayon temple, for example, has detailed bas-reliefs featuring images of families making dinner, men drinking together, and women going into labor. It has 37 towers and is decorated with 216 faces.
Ta Prohm is one of the most photographed temples (and famous for being featured in “Lara Croft: Tomb Raider”). It is purposefully unrestored, and eerily magical as it's been near-swallowed by the jungle: a beautifully tangled mess of ficus and silk tree roots.
Angkor Wat, the most famous of the temples, is even on Cambodia's flag, and a source of local pride.
It was built as the spiritual home of Hindu god Vishnu, and is one of the largest religious monuments in the world, said to represent heaven on earth. Unlike most other temples in the complex, it was never abandoned, and has pretty much been in continuous use since it was built. It's still a place of worship today.
Angkor Wat features more than 3,000 carvings of asparas — female spirits — supposedly with 37 different hairdos.
It is also said to be a miniature replica of the universe.
Angkor Thom is another huge structure. Spread across four square miles and boasting a fortified wall and moat, it’s said to have been the world's largest city in the 12th century.
Giant statues are sprinkled throughout the complex.
Banteay Srei may be a small temple, but it's one of the most lavishly decorated ones. Dedicated to the Hindu god Shiva, it's built from a pinkish limestone and features intricate designs on practically every surface.
While hundreds of years old, the temples feature sophisticated hydrological engineering systems and a massive system of canals and reservoirs that can still be viewed today.
No one really knows why the cities were abandoned. Some claim that a bloody battle caused people to evacuate, others that it was caused by changes in religion (Khmer's Hinduism was replaced by Buddhism around the 13th and 14th centuries). Others again speculate that the elaborate water systems failed, and that people had to move in order to find water.
Angkor was always known to locals, though it remained abandoned and increasingly shrouded by the surrounding jungle. Locals took Westerners to the site as early as 1586, and throughout the next centuries, but it wasn't until the end of the 19th century that European archaeologists took an interest thanks to Louis Delaporte and Adolf Bastian, who vocally promoted the site, leading to the 1907 to 1970 restoration efforts by the École française d'Extrême-Orient.
Civil war intervened, and restoration efforts weren't resumed until 1993 when UNESCO launched a major restoration campaign after naming it both a World Heritage site and a World Heritage in Danger in 1992.