Visit the Bridge on the River Kwai, part of the infamous Death Railway which was bombed by the Allies during WWII and has since been rebuilt. You also visit the nearby war cemetery. It is estimated that over 16,000 POWs died while building the Death Railway to Myanmar, of which the bridge was only a small part. From here you will take the train to Tham Kra Sae station which will include crossing the bridge over the River Kwai and also the Tha Kilen viaduct.
On arrival you stop for some lunch at a local restaurant before continuing to Hell Fire Pass, 50 miles (80 kilometers) northwest of Kanchanaburi. This was the name given by the prisoners to the largest of a series of mountain cuttings through soil and rock, which were accomplished with minimal equipment.
From here you can look out onto Myanmar as well as climbing down onto part of the famous railway. You have time to explore the area here and if you wish you can take a short walk along the old railtrack heading to Myanmar before returning to your hotel.