This temple is among the oldest and largest in Bangkok, and Somerset Maugham declared its roofline the most beautiful. It was begun by Rama I and finished by Rama III; Rama II carved the panels for the viharn doors. It houses the beautiful 14th-century Phra Buddha Shakyamuni, a Buddha image that was brought from Sukhothai. The ashes of King Rama VIII, Ananda Mahidol, brother of the current king, are contained in its base. The wall paintings for which it is known were created during Rama III's reign.

Outside the viharn stand many Chinese pagodas, bronze horses, and figures of Chinese soldiers. The most important religious association, however, is with the Brahman priests who officiate at important state ceremonies, and there are two Hindu shrines nearby. To the northwest, across the street, is the Deva Sathan, which contains images of Shiva and Ganesh; and to the east, the smaller Saan Jao Phitsanu is dedicated to Vishnu. The huge teak arch -- also carved by Rama II -- in front is all that remains of an original giant swing, which was used until 1932 to celebrate and thank Shiva for a bountiful rice harvest, and to ask for the god's blessing on the next. The Minister of Rice, accompanied by hundreds of Brahman holy men, would lead a parade around the city walls to the temple precinct. Teams of men would ride the swing on arcs as high as 25m (82 ft.) in the air, trying to grab a bag of silver coins with their teeth. Due to injuries and deaths, the dangerous swing ceremony has been discontinued, but the thanksgiving festival is still celebrated in mid-December, after the rice harvest.