Spolia (Latin, ‘spoils’), repurposed building stone for new construction, or decorative sculpture reused in new monuments, is the result of an ancient and widespread practice whereby stone that has been quarried, cut, and used in a built structure, is carried away to be used elsewhere. The practice is of particular interest to historians, archaeologists and architectural historians since the gravestones, monuments and architectural fragments of antiquity are frequently found embedded in structures built centuries or millennia later.

Source: Spolia – Wikipedia