The southern boundary of Pratunam is marked by the Saen Saep Canal. This canal was dug during the reign of King Rama III in the mid-nineteenth century to connect the Chao Phraya River with the Bang Pakong River to the east. When Saen Saep was connected with Maha Nak Canal and Krung Kasem Canal, a gate was required to control the water level between them. Pratunam means "water gate". It was not developed until the 1960s when rice fields dominated the landscape. Around that time, a fresh produce market was set up near the Indra Hotel at Ratchaprarop Road. Since then more markets have set up here, and the whole area has become known as a local marketplace.