The Bridge on the River Kwai at Kanchanaburi, 2 or 3 hours west of Bangkok, is part of the Thailand-Myanmar railway built during WW2.
It's called the Death Railway due to the number of workers who died during its construction.
Estimates are 16,000 Prisoners of War (mainly British and Australian) and 90,000 - 100,000 labourers from Thailand, Malaysia and Myanmar.
The railway no longer reaches Myanmar as much of the line was broken up and used for building materials.