Mass Grave in Paris

Archaeologists digging under a Monoprix super market in Paris have discovered hundreds of skeletons, 150 of them in a single mass grave. The site was once the location of the Hôpital de la Trinité, but records said the bones from the hospital cemetery had been moved to the Paris catacombs in the 18th century. No radiocarbon dating or DNA analysis yet, but the archaeologists suspect that at least the people in the large mass grave were victims of the plague.

Which might explain why they weren't moved; maybe in 1750 nobody wanted to dig into an old plague pit, or handle the remains.