Ayutthaya
An hour and a half north of Bangkok by train (or longer and more interesting by river cruise), Ayutthaya was the capital of Siam from 1351 until the Burmese sacked it in 1767. The brick-and-laterite ruins of the royal city — Wat Mahathat with the famous tree-rooted Buddha head, Wat Phra Si Sanphet, Wat Chaiwatthanaram on the riverbank — are now a UNESCO site that can be cycled in a long afternoon. Sunset at Wat Chaiwatthanaram, with the prang silhouettes against an orange sky, is the photograph most visitors come for.