Location - Soi Kasem San 2, just off Rama I road. The easiest way to get here is from the National Stadium skytrain station and follow the signs to the end of this quiet Soi. Google Map location.
Jim Thompson is the American businessman credited with saving the Thai silk industry and turning it into what it is today. His house is actually a collection of 6 traditional Thai houses he had dismantled from various places and then rebuilt here in this quiet corner of Bangkok.
The man himself mysteriously disappeared while walking in Malaysia and hasn't been heard from or seen since. His house has now been given over to the Thai Fine Arts Department and is open as a museum. It is open most days and guided tours operate regularly in many languages.
Jim Thompson's House Website.