Ayutthaya (full name Phra Nakhon Si Ayutthaya, also spelled "Ayudhya") city is the capital of Ayutthaya province in Thailand. Located in the valley of the Chao Phraya River. 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. Ayutthaya became the second Siamese capital after Sukhothai. Its remains, characterized by the prang (reliquary towers) and gigantic monasteries, give an idea of its past splendour. 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.
Ayutthaya is named after the city of Ayodhya in India, the birthplace of Rama in the Ramayana (Thai, Ramakien); Phra is a Thai royal and noble title; Nakhon designates an important or capital city; Thai honorific Sri or Si is from the Indian term of veneration Sri. The city is located at the junction of the Chao Phraya, Lopburi and Pa Sak rivers, and on the main north-south railway linking Chiang Mai to Bangkok. The old city is on an island formed by a bend of the Chao Phraya on the west and south sides, the Pa Sak on the east side and the Klong Muang canal on the northern side.