To protect their outer walls, many castles were surrounded by a moat (a water-filled ditch). Some castles used rivers as part of their moat, but most moats were man-made.

为了保护城堡的外墙，很多城堡都在四周建造了护城河。一些城堡利用河流作为护城河的一部分，但大多数护城河是人工修建的。