Most cemeteries in Europe have been destroyed to make space for urbanisation. The underground of Paris is full of bones from those cemetaries (catacombs of Paris). It's fairly common as outside of a few aristocratic families, people keep a very short memory of their ancestry. I have a very vague knowledge of who my ancestors were back to the mid XIX century and nothing prior. Hard to have any emotional attachment to people you never heard about. So if no one cares, better to build a parking lot!