For place and period, Western Europe pre-Nineteenth Century, though relevant comment on other places is welcome.

There's stories of this church or that castle or this bridge containing, or having been erected upon, the grave of an unfortunate sacrificed to provide spiritual reinforcement to the edifice; London Bridge being, as far as I know, the 'classic' example.

The book that brought the topic to mind made reference to tales that various walls had been found to have skeletons beneath them, or that a hole knocked into a structure (at a point indicated by ancient folklore) revealed a hidden crypt, and that immuring sacrifices beneath structures was once a venerable and widespread custom; however, the book in question was an old one, citing other old books (Edward Tylor's Primitive Culture and Andrew Lang) and I'm wondering if more modern scholarship has turned anything up.

I don't doubt that it features in legend and folklore about the grisly heathenisms of olden-days, but was such a custom truly practiced?