This tiny museum housed inside a beautiful wooden hall is part of the Wat Sai complex. Built in 1932, it was occupied by Japanese troops during WWII in 1941. Today, it houses many of the temple's ancient relics including a couple of gold Buddhas, ornate monk's seats, tons of beautiful ancient manuscripts and the temple's brass bell, dating from the reign of Rama III – temporarily used for raising the alarm during WWII.