Walls and towers Thick stone walls and tall towers kept the castle's inhabitants safe from attack, even when an enemy army besieged (surrounded) the castle.

While many point to the "Keep" or "Moat," the most critical feature of a medieval castle was arguably its siting and topography. A castle’s primary purpose was defense and control, so being built on a high "motte" (hill) or a rocky outcrop provided a massive strategic advantage. This height allowed defenders to see enemies approaching from miles away and made it physically exhausting and dangerous for attackers to charge upward while being pelted with projectiles. Beyond the land itself, the Curtain Wall—the massive outer stone wall—was the most vital man-made feature. It acted as the first major line of defense, often several meters thick and reinforced with "bastions" or towers that allowed defenders to shoot along the face of the wall (flanking fire). Without a strong curtain wall and a high vantage point, the internal luxuries of a castle would be useless, as the structure would be easily overcome by even a modest besieging force using basic rams or ladders.