Angkor, the former capital of the ancient Khmer Empire, is one of the greatest and most spectacular Hindu religious sites in the world. Construction of this elaborate temple complex - built in honour of the god Vishnu - began in AD 879 during the reign of King Suryavarman II and was completed in 1191. It lay concealed for many years, however, until the site was discovered by Frenchman Henri Mahout in 1860. The central complex, Angkor Wat, features an elaborate, unmortared 66-metre (215-foot) central tower surrounded by four smaller towers. Stretching around the outside of the temple complex is an 800m-long (2625ft) bas-relief, the longest in the world. This is Cambodia's most iconic sight, and particularly popular at sunset among tour groups. The temple is so synonymous with the country that it dominates the national flag, and to visit it today is to marvel at the scale of its ambition, built as it was in the 12th century.