After a little searching I actually found a website for it and wow. Looking at the website I can see that it is a veritable maze of buildings and each one having a specific value: the Sermon Hall, Sunthorn Phu's quarter, Phra Ubosot (Chapel), Ho Tri (Library),
Phra Wiharn (Shrine), Thanon Maha Chai (Gate) and Samran Rat (Gate) - here's a map and here's some history.
"King Rama III was a faithful king. Devoted to Theravada Buddhism, the king encouraged Buddhist education among the monks as well as took various temples under his patronage. Providing personal funding for reparation of those temples, massive reconstruction and renovation of monastery both inside and outside of Bangkok were taken place during his reign."
It may not look like much to the casual observer because it does have a wall around it - so take a closer look if you are able.