Also called Wat Cha Ram, the place is not dated by historians but the temple was mentioned in stanza 23 of Niras Nakhonsawan which was composed during the reign of King Narai. So it would date from before that time.
Few tuk-tuk drivers offering tours have Wat Phra Ngam on the photos they show to tourists to decide together which places they will take you to visit. Note that there are a lot more crowd visiting the temple on weekends and holidays in Thailand.
Wat Phra Ngam is a temple and when you visit a temple in Thailand there are some rules to know and follow :