Ayutthaya was the capital of the kingdom of Siam for more than 400 years, one of Asia's largest and richest trading cities, visited by Arab, Persian and European merchants. It lies about 80 km north of Bangkok. Its historical park, on the UNESCO list since 1991, is scattered with red-brick towers, and at Wat Mahathat a stone Buddha head sits in the roots of a tree. You can return to Bangkok by boat on the Chao Phraya.