There are two galleris
Sightseeing in Siem Reap/Angkor picture - The Bayon is the only temple to have two concentric galleries sculpted with bas-reliefs. The internal gallery is complete in its ornamentation & was almost exclusively reserved for mythological Hindu subjects. The outer gallery (this one), which was not completed, was dedicated to scenes of everyday life & to certain historic episodes, especially processions & battles, from the reign of Jayavarman VII.