Concentric Castles

Concentric Castles

Concentric castles were a significant representation of medieval military architecture. These were much larger construction than Motte and Bailey castles and consisted of the best usage of angles. These were stone castles with two or more concentric curtain walls. In such designs, the outer walls were constructed lower than the inner walls while giving an illusion that one castle is nested inside the other castle.

Concentric Castles were a series of defensive structures. Each wall of these castles included rounded towers, which helped defenders keep an eye on their enemies. Sometimes, the towers and curtain walls were also constructed with a lake around them, making entry difficult for attackers.

History of Concentric Castles

Syrian knight's fort Concentric Castle
Syrian knight’s fort Concentric Castle, by Lin Gaozhi (林高志), is licensed under CC BY-SA 4.0

Before the 12th century, castles were designed using stone, earth, and timber. But by the late 1100s, these castles started looking old-fashioned. Also, these materials were not very durable, and the castles designed using them couldn’t stand steady during attacks. So, to increase durability, the construction of the stone castles started. These castles were durable but didn’t offer defenders better opportunities to attack enemies. It is where the concentric castles were introduced to the world.

Concentric castles were more significant, defensive, and durable constructions than Motte and Bailey castles and stone castles. These castles were developed to utilize all angles for medieval military uses. The primary idea behind their construction was to build a castle within a castle. Two independent rings of curtain walls were built around it. They worked as concentric castles birds-eye view, and vantage points for archers to attack the enemies.

Some concentric castles, like the ones built by Edward I in the 1290s, included iron rings. They were costly, durable, and nearly faultless. We will also discuss concentric castle’s strengths and weaknesses in this article. So, keep reading.

When were Concentric Castles built?

Concentric castles were built in the 12th and 13th centuries. In the mid-1200s, the royalties realised the importance of concentric castles. The best examples of concentric castles, like Caerphilly Castle, Wales, were built around 1270. These castles included two rings of curtain walls into separate obstacles for attackers to overcome. Each wrapping wall of these castles had its importance and increased the defensiveness of the castle. These castles are the best examples of development in siege technology.

Features of Concentric Castles

The most distinct aspect of concentric castles was that they included two castles in one. Here is a list of major features of Concentric Castles:

Outer Gatehouse

Outer Gatehouse
Outer Gatehouse, by Elliott Brown, is licensed under, CC BY-NC-SA 2.0

Just like any ordinary castle, the concentric castle included an outer gatehouse. It was the house standing by the gateway and worked as the birds-eye point near the main entrance.

Multiple Inner Gatehouses

Multiple Inner Gatehouses
Multiple Inner Gatehouses, by diamond geezer, is licensed under CC BY-NC-ND 2.0

Multiple inner gatehouses were built in the castle (often over the castle’s boundaries) to attack the enemies. Some gatehouses were also used to house soldiers, while some were used as the prison.

Outer and Inner Bailey

Bailey is the outer wall of the castle. The concentric castles included outer bailey and inner bailey. If the enemies tried to access the inner bailey through the outer gatehouse, they would get attacked. Both inner and outer bailey included the extra buildings, soldiers, servants, and animals.

Outer and Inner Curtain Wall

Outer and Inner Curtain Wall
Outer and Inner Curtain Wall, by Elliott Brown, is licensed under CC BY-NC-SA 2.0

Curtain walls were fortified walls built around the castle. They linked towers together. The outer curtain walls maintained the outer structure of the castle while covering it properly. The inner curtain walls were designed higher than the outer curtain walls so that defenders could quickly look down and attack their enemies.

Water Filled Moat

Water Filled Moat
Water Filled Moat, by Michael & Sherry Martin, is licensed under CC BY-NC-ND 2.0

Water filled moat (a ditch) was constructed around the castle to make it inaccessible for enemies from any other point than the gatehouse.


The large keep, considered the most secure place in the castle, was constructed in the centre of the castle. It was used to access the gatehouse from the inner bailey. The enemies, who somehow managed to get through the first gatehouse, would get attacked around the keep if they tried to enter it.

Death Hole

Death Hole
Death Hole, by Ken Lund, is licensed under CC BY-SA 2.0

The space between the two walls of the castle is known as the death hole. The concentric castle included many death holes that were used to trap the enemies within the walls.


Postern, by Konstantinos Plakidas, is licensed under, CC BY-SA 4.0

Postern is a small escaping gate built at the backside of the castle. The castle’s occupants used to access it during emergencies.

Advantages of Concentric Castles

The overall design of concentric castles was virtually impregnable to enemies, which was one of the main advantages of concentric castles. Concentric Castles were almost impregnable to the enemies, which was one of the main advantages. The only option left with the attackers at that point was to surrender. Other advantages of concentric castles were:

  • These castles included many layers, and each of them offered different obstacles to the enemies. The enemies needed to penetrate all the walls once they passed the gatehouse and barbican.
  • The higher inner walls were tough to reach for the enemies. Also, it offered concentric castles a birds-eye view and helped defenders keep an eye on enemies for an attack.
  • The concentric castle was large so that it could house more defenders.
  • The lookout points of the castle offered a view of the entire surroundings. They were built in symmetrical shapes (offering a better view), which required fewer men to keep an eye around the castle.
  • The round towers of the castle were tough to mine.

Disadvantages of Concentric Castles

Despite the advantages, Concentric Castles weren’t affordable or practical. Also, the enemies could easily observe their designs and make their siege plans accordingly. Here is a list of other disadvantages of the concentric castle:

  • The concentric castles were expensive to build, and not everyone could afford them.
  • Compared to Motte and Bailey Castles, it required more time to build Concentric Castles. Because the time needed to build was quite long, the castle was often no longer needed by the time it got finished.
  • The concentric castle attacking strategy put a huge burden on royal treasuries. Also, the elaborated defensive system required more defenders. Sometimes, paying each defender became tough for the castle owners. 


Concentric castles were considered the safest form of medieval castles. These castles were designed with the strongest defense system. However, concentric castles had their weaknesses as well. It required massive resources, workers, and time to build these castles. It used to take several years to build the castles.

The remains of concentric castles can be seen around the world. Major examples of concentric castles are:

  • Castle of Marget (Syria)
  • Caerphilly Castle (Wales)
  • Belvoir Castle (Israel)
  • Harlech Castle (Wales)
  • Munzenberg Castle (Hesse)
  • Kidwelly Castle (Wales)
  • Byzantine Castle (Korykos)
  • Rhuddlan Castle (Wales)

Visit these concentric castles and expand your knowledge about their defensive structures.

Have you visited any of these castles before? If yes, why not share some beautiful pictures with us!
You can email us your pictures of the castle at Please use the name of the castle in the subject line.
Also, don’t forget to mention your name and social media profile link if you want the credits!

He is a versatile E-Learning Support Officer and former Academic Officer at the University of York, United Kingdom. Not just an expert in education and technology, Debayan also has a deep love for castles and mountains. With a passion for travel, having explored 168+ cities worldwide, and a keen eye for photography, He brings a unique blend of experiences to the table. Specializing in E-learning content, IT support, AR development, and software engineering, Debayan has made a significant impact, educating over 200,000 students on Udemy.

Leave a Reply