A castle was built to withstand attack from enemy. Castle builders added many defensive features to make their castles difficult to attack. Many castles were built on high ground with clear views of the surrounding land.

Moats
Attackers were easy to shoot whilst swimming or rowing across the moats filled with water. Moats reduced the risk of tunnelling under the castle.

Ramparts
Ramparts were steep banks of earth or rubble. Attackers had to climb over them to get closer to the castle.

High walls
The walls of the castles were very high making it hard for attackers to climb over.

Curtain walls
Tall thick curtain walls surrounded the castle buildings like a strong shield. There were few doors in the wall thus limiting access to the castle.

Flanking Towers
Towers built as part of the curtain wall. Castles with curtain walls with flanking towers were more difficult to capture. A good early example of a castle with flanking towers is Framlingham in Suffolk. Along the curtain wall, at intervals, are thirteen square or rectangular towers

Battlements
The top of the castle walls were the battlements, a protective, tooth shaped parapet often with a wall walk behind it for the soldiers to stand on. The defenders could fire missiles through gaps (crenels). The raised sections between, called merlons, helped to shelter the defenders during an enemy attack.

Machicolations
These were stone boxes that projected from the walls of castles and had holes in the floors for dropping stones or boiling oil on attackers. Wooden versions of these were called hoards.

Gateway defences
The entrance to the castle was always its weakest point. Drawbridges could be pulled up, preventing access across moats. Tall gate towers meant that defenders could shoot down in safety at attacks below. The main gate or door to the castle was usually a thick, iron-studded wooden door, that was hard to break through. A spiked wooden or metal barrier, called portcullis, helped protect the doors from fire and battering. It was lowered by chains from a chamber above the gateway. The word portcullis comes from the Old French porte-coleice, meaning sliding door.

Murder Holes
Murder holes were openings in the ceiling just in front of a gate or in the passage beyond. They were so called because it was believed that they were used by defenders in the chamber above to drop hot liquids down on the unfortunate attacker.

Round Towers
It was harder for attackers to make round towers collapse. Unlike square towers they had no corners, which collapsed if holes were dug underneath the foundations.

Arrow and Gun Loops
These provided a safer means of firing arrows on the attackers of the castle. They are found in many different styles on the curtain wall and towers of the castle.