After the foundation of Bangkok in the Ko Rattanakosin area in 1782 and the construction of the Grand Palace, King Rama I ordered the construction of the Wat Pho. The temple was built on the site of an older, Ayutthaya era temple named Wat Photharam right next to the Grand Palace. During the reign of King Rama III the temple complex was renovated and enlarged which took over 16 years to complete.