The famous temple of Angkor Wat, shrouded in mist. Angkor is pretty well-known, but I'll add that, interestingly, a team of researchers recently concluded that Angkor had been the largest preindustrial city in the world, with a population of up to one million and an elaborate system of infrastructure connecting an urban sprawl of at least 1,000 square kilometres to the temples at its core. In comparison, Angkor's closest rival, the Mayan city of Tikal in Guatemala, was between 100 and 150 square kilometres in total size.
Stamp showing a carving from the Banteay Srei temple complex located in the Angkor area. The temple was built in the tenth century and is renowned for its intricate and well-preserved carvings.