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Spiral staircases -

While taking up less space is an advantage, medieval castle builders had a different purpose in mind when they included a spiral staircase, which tend to turn clockwise as you ascend.

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Spiral staircases -

Since most people are right-handed, if a knight tried charging up the spiral stairway holding his sword in his right hand, his ability to swing a wide arc would be limited by the wall, giving a retreating defender a potentially life-saving lead.

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Arrow slits -

These long, narrow slits found in the heights of castle walls were made so defenders could fire arrows while still benefiting from maximum protection.

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Arrow slits -

Later on, the slits would be horizontal as well as vertical to provide a wider field of fire.

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Murder holes -

Also called machicolations, murder holes offered the chance to attack anyone in close proximity to the castle. They are simply a series of projecting buttresses near the tops of the outer walls.

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Murder holes -

The structure would have an open bottom so that when enemies arrived beneath it, defenders could drop something—either something heavy or dangerous like hot oil—on top of the attacker.

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Crenellations -

Also called battlements, these are the most characteristic element we think of when we think of a castle. The gapped-teeth-looking design tops the outer walls, offering defenders both cover from enemies and a space to take a shot.

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Chemins de rondes -

The French term means walkway, but in medieval castles these walkways were built into the top of its walls.

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Chemins de rondes -

The pathways were protected by battlements, and allowed defenders to move around in a relatively safe manner while also giving them an advantageous position from which to fire back.

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Taluses -

A conventional wall tends to extend straight up from the ground, but some medieval castles flared the bottom section of the wall outwards, called a talus. It forced attackers to keep a greater distance from defenders inside, and it was harder for attackers to use siege engines (large devices used to break through walls) or ladders.

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Taluses -

A wall that is thicker on the bottom makes breaking it down much harder. The diagonal slant also allowed defenders to drop rocks from high up the walls and watch them rebound off the talus and hit the enemy with greater force.

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Bastion -

This extra-fortified element of the castle wall was typically built in the form of a round tower protruding from the wall at corners of the castle’s structure.

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Bastion -

As cannons began to improve in the 15th century, castles became more vulnerable, and the bastion was a way of strengthening the castle's exterior, making it as impenetrable as possible.

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Moat -

We've all heard of the moat, which was essentially a ditch around the castle walls that was filled with water to provide a barrier against attackers who would first need to find a way to cross the moat before launching an effective attack.

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Moat -

This genius addition also made it near-impossible to crumble the castle walls or tunnel under them. They could also be great traps if there were pointed stakes driven into the floor of the ditch.

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Drawbridge -

If the castle had a moat, it would typically need a bridge. Making it retractable was a fantastic way to eliminate easy access from enemies. Usually it would lead over the moat to the gatehouse, and once raised it would form another obstruction to help defend the castle.

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Gatehouse -

As fortified as a castle might be, it still needs an entrance, and that is immediately one of its weakest points. That’s why gatehouses, often outfitted with murder holes, were constructed in front of the gateway.

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Portcullis -

The criss-crossed portcullis gate is common in the entrance to the gatehouse. The bottom often had sharp points to threaten anyone brave enough to pass beneath it, and sometimes there would be two portcullises on either side of the gatehouse to trap enemies between them.

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Donjon -

Also known as the keep, this donjon is the multi-floored tower that served both as the heart of castle life as well as the last refuge against attackers. It typically contained various rooms with specific functions, like dining rooms and kitchens, as well as turrets (small towers) built in as firing points.

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Donjon -

In the medieval age, many castles fell into disuse or hard times, and the term donjon became the dungeon, transforming from the most protected refuge to the most guarded prison.

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Oubliette -

The term in French signifies a forgotten place, and it was where prisoners were left to rot. This special kind of medieval dungeon is characterized by having a trapdoor entrance in the ceiling of the cell.

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Ravelins -

A ravelin was a stronghold, typically triangular in shape, built a short distance from a castle’s main walls. It was the first line of defense against attackers, and the triangular shape allowed defenders to fire on enemies from a variety of angles.

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Ravelins -

The ravelin provided a barrier against artillery attack on the castle’s main walls, but, more interestingly, they were made with lower walls on the castle side so that if an enemy seized control of the ravelin, they’d have no cover from defenders high on the castle’s ramparts.

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Garderobe -

In our modern-day glamorization of the medieval times, we forget they didn’t have plumbing! The latrine was called the garderobe, and consisted of a small room either just inside the castle wall or protruding out from it with a hole built into the floor and a chute leading down.

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Garderobe -

The French name signifies a small room where you keep clothes, and some reports say that the small room of the toilet would also double as a closet for fine clothes because it was believed that ammonia would protect the coats and cloaks from moths or fleas.

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Bossed stones -

Bossed stones have an unfinished, rugged plane facing outwards, and for a long time their appearance confused experts who couldn’t figure out why some stones were smoothed and others not. Eventually, they discovered that the rugged stone better diffused the effect of projectile rocks.

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Hourdes -

Hourdes were like temporary wooden balconies used when a medieval castle came under attack, offering an extra vantage point. Defenders would reportedly cover the timber with soaking wet animal skins to make it difficult for attackers to set them on fire, until finally permanent stone-built defenses took their place.

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Bartizan -

Also known as an échaugette, a bartizan is a kind of mini-tower protruding from a long, straight stretch of castle wall. They allowed defenders a space protected on all sides, with a wide field of vision to serve as both a look-out and a position to fire back.

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Secret passages and rooms -

Though secret passages date far beyond the medieval times, castles made good use of them as routes to hidden rooms or as a means of escape. The doorway to a secret passage would often be disguised or look like a simple blank wall.

See also: The world's most fascinating fortresses.

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