Two rivers meet at Kanchanaburi. The Khwae Noi and the Khwae Yai join on the edge of town to form the Mae Klong, and almost everything that made this place famous, and infamous, happened along their banks. Most people know it from a film title, but the bridge over the Khwae Yai is only one short piece of the Thailand–Burma Railway that the Japanese army forced through the jungle in 1942 and 1943, using Allied prisoners of war and a far larger number of conscripted Asian labourers. Tens of thousands of them died, and the line earned its other name, the Death Railway.
It is worth giving the history an hour before you think about lunch. The Kanchanaburi War Cemetery sits right in town, immaculately kept, rows of low bronze plaques under rain trees, and the railway museum beside it explains the scale of the thing better than any bridge photo. Walking across the bridge itself is allowed, carefully, between the occasional tourist train. Early morning is the time: the light is soft, the vendors have not set up yet, and the river is still.
The ride out from Bangkok is not the attraction. Route 4 and then Route 323 run west through flat, hot country of sugar cane and roadside stalls, with trucks and a fair amount of traffic until Nakhon Pathom falls behind. Keep in mind that motorcycles are not allowed on Thailand's expressways and motorways, so the ordinary highways are your world. Once you are past Kanchanaburi, though, things improve. Route 323 follows the Khwae Noi valley north-west towards Sai Yok and Hellfire Pass, with limestone hills closing in and the traffic thinning, and the side road towards Erawan National Park and its terraced turquoise falls is a lovely detour of an hour or so.
For a food stop the town makes things easy. There are floating restaurants on rafts along the river, plenty of noodle shops on the main streets and a night market where you can eat for very little. Fuel is everywhere, from big branded stations to roadside pumps. Drink more water than you think you need: from March to May the heat in this valley is serious, and the best riding hours are the first three of the day and the last one before dark, when the hills turn blue and the river picks up the sunset.