The Old City Moat, known in Thai as Khlong Khoo Meuang (Deum), i.e. ‘(Original) City Canal Ditch’, at the sluice gate with the Chao Phraya River. The canal was dug in 1783, on the orders of King Rama I, after moving the capital from Thonburi to its present location in Phra Nakhon.

In the West, the capital already had the Chao Phraya River as its natural border, and with the canal enclosing it in the East akin to the moat of a fortified city, an ‘island’ was created, which became known as Koh Rattanakosin.