The City Pillar shrine in Ayutthaya.
The Ayutthaya City Pillar (Lak Muang) shrine is located next to the roundabout near Wat Phra Ram. This shrine, and the pillar within it, is a modern construction erected in the twentieth century. While there is some evidence that ancient Ayutthaya may have had a city pillar, nobody is sure where it was located. The significance of the city pillar changed substantially during the Bangkok era, and it wasn't until the 1990s that provinces were actually directed to erect city pillars in their capital cities.
People come to city pillar shrines to make offerings and pray for good fortune, pregnancy and other boons. There's a rather amusing story about one teacher's experience with the shrine on the Ayutthaya Info web site.