Angkor is the most important ancient monument in Southeast Asia, located in Cambodia's Northern Province of Siem Reap. It comprises of temples, basins, dykes, reservoirs, canals, and communication lines and encompasses around 400 sq. km. The capital of the Khmer Empire was Angkor for centuries. Angkor Wat, the Bayon, Preah Khan, and Ta Prohm, which are proof of Khmer architecture, are inextricably strapped to their geographical environment and filled with symbolic meaning. The Khmer Empire, which ruled most of Southeast Asia from the 9th to the 14th century, shaped the region's political and cultural development. In the 1840s, the French explorer Henri Mouhot "rediscovered" Angkor, writing that the site was "grander than anything bequeathed to us by Greece or Rome." It was designated as a World Heritage Site by UNESCO in 1992.