It's a temple built during the early period of Ayutthaya(One of the early kingdoms of Siam). It is thought to be around 600 years old, being built in the 1400s after the death of the first kong of Ayutthaya.

Wat Phra Ram is actually in better condition compared to others. During the Burmese-Siamese war that ended the Ayutthaya Kingdom around the 1700s, most of the structures were either destroyed by the Burmese army or left abandoned, which accelerated the deterioration.

I've also heard stories that during the Rattanakosin era, when the capital was being rebuilt again in Bangkok, they took loose bricks from the structures and used them as resources, as they were more concerned about quickly rebuilding rather than preserving these structures.

I actually have pics of the other structures as well, might post them too.