AS DAWN breaks over Bangkok each morning, thousands of residents begin to use the waterways on which their city depended long before traffic congestion became fashionable. Ageing boatmen use long poles to paddle their long, narrow craft across canals, coated with purple lilies in a method of transportation that has changed little in centuries. The ferry ride costs as little as one baht (about HK$0.32) each way, depending upon the route. Other commuters roar up and down the extensive klongs, or canal network, in motorised water taxis. Bangkok was founded on water and the dozens of canals snaking out from the Chao Phrya - the celebrated River of Kings - performed practical defensive functions as well as providing a cheap and efficient means of getting around. The city was loosely modelled on Ayutthaya, its forerunner as capital upstream on the Chao Phrya, which was destroyed by the Burmese in 1767. Like Ayutthaya, Bangkok was completely surrounded by water and swamps as a natural defence against elephant-borne invaders, eventually developing a canal system that rivalled Venice. The Chao Phrya remains the commercial artery of Thailand. The 90-kilometre journey to Ayutthaya offers the most accessible and fascinating glimpse of the Chao Phrya. Tours are arranged daily and depart from riverside hotels in Bangkok on all-day excursions by boat and coach, returning in late afternoon. Chugging past the Grand Palace and the Temple of Dawn, boats head up-river through the bustle of river commerce and a jumble of ancient teak stilt houses built over the water jammed in between rambling colonial mansions. Then they clear the city and enter the open plains, where small communities till fields of paddy and corn behind lumbering buffalos and load husks into small boats. Cruises end at the palace of Bang Pa-in, 14 kilometres south of Ayutthaya, which was once a summer retreat for Thai kings. It boasts a curious mixture of European and Oriental buildings. Visitors make the remaining 30-minute trip to Ayutthaya in small boats or by road. There is also a rail stop at Bang Pa-in. Once greater than Paris, London or Rome, Ayutthaya was founded in 1350 and ruled Thailand for 400 years. Designed around an island of encircling rivers, including the Chao Phrya, it was the country's spiritual and administrative heart. Over a period of several centuries, craftsmen built a magnificent collection of temples and palaces linked by canals. The Burmese, reputedly allowed through the gates of the impregnable fortifications by traitors, razed the city to the ground. Some of the more spectacular temples have been rebuilt, but it is difficult today to envision the grandeur that was once Ayutthaya. The most important temple was Wat Phra Sri Sanphet, which once included a 16-metre image of a standing Buddha moulded totally from gold. It is best to hire a longtail boat for one hour to see the ruins, which are mostly located on islands created by the criss-crossing canals. Getting there: Two luxury services, Oriental Queen 1 and 11, are operated daily by the Oriental Hotel (telephone 236 0400), leaving at 8 am and 5 pm. The day service includes lunch and the night departure dinner. Ayutthaya Princess (telephone 255 9200) sails daily except for Sunday, leaving at 10 am. The 16-passenger Mekhala, run by Asia Voyages (235 4100), has daytime and overnight schedules on a beautiful, converted rice barge. Departure times vary.