Mystery Stones

We recently had cause to visit the hospital in Poitiers, and it threw up a bit of a totally unexpected mystery.

By the main entrance to the hospital are these pieces of stone, taken from the 12th century church at Melle. They aren't 12th century originals, but 19th century replacements. Quite why they have themselves been replaced, and why they are outside the hospital, I do not know. At first I assumed that the church was on the site of the hospital and had been demolished, but the church at Melle still stands - assuming it's this one.