Ayutthaya is the capital of Ayutthaya province and was a former capital of Thailand. The city was founded in 1350 by King U Thong, who went there to escape a smallpox outbreak in Lop Buri and proclaimed it the capital of his kingdom, often referred to as the Ayutthaya kingdom or Siam. It is estimated that Ayutthaya by the year 1600 CE had a population of about 300,000, with the population perhaps reaching 1,000,000 around 1700 CE, making it one of the world’s largest cities at that time. In 1767 the city was destroyed by the Burmese army, resulting in the collapse of the kingdom. The ruins of the old city now form the Ayutthaya historical park, which is recognized internationally as a UNESCO World Heritage Site.