Here you see a part of the old jewish cemetery in Prague. Some people believe its more than thousand years old. By jewish law it is especially forbidden to remove a tombstone and when there was no more area available the then existing tombstones where covered with earth and the people started again to bury. 12 burial layers are discovered and 12000 tombstones are visibly today. The total burials is estimated on a total of 100000 and the oldest one is from 1439. It was in use from the early 15 century till 1787. For more taphophile tragics look here.