Phra Mondop (Library)
This building is situated to the rear of Phra Thep Bidorn on the same base. King Rama I ordered its construction to the north of the Ubosot to replace the former Phra Monthien Tham which was burnt. This earlier building had been constructed in the middle of a pond to prevent attack by termites - a common practice during the late Ayutthaya and early Bangkok period. Its purpose was to house the Tripitaka (Buddhist scriptures) which he had revised at Wat Mahathat in 1788 (the previous edition having been lost in the sack of Ayutthaya in 1767).
The library was extensively restored during the reign of King Rama III to commemorate the 50th anniversary of Bangkok. The cruciform building has a mondop-style roof. Originally it was on a higher base which raised it above the Ubosot. Accordingly when King Rama IV built Phra Thep Bidorn and Phra Sri Rattana Chedi, this building was seen to be too tall and was lowered.