Rochester Castle is a stone keep castle in Kent, England, built by the Bishop of Rochester around 1090 AD. While these castles are quite strong, they are not impregnable: many groups besieged this castle over the years and control of it had switched hands many times. Constructing this castle took a great deal of the king’s wealth at the time. Towers were added to it in the year, 1127 by Archbishop William de Corbell. The tallest point of this castle reaches over 110 feet (33.5 meters).
Rochester Castle, and other square keep castles feature stone construction. These castles were designed to stand for many centuries. Resistant to rot, these castles were incredibly strong and could outlast any wooden structure. The strength of stone allowed builders to construct square keep castles, such as Rochester Castle, to great heights, which allowed people to see potential enemies advancing from miles away. Rochester Castle’s walls were built to a thickness of over ten feet (3.05 meters) in certain places, making the castle very difficult to attack and destroy.
Despite the strength of castles like Rochester Castle, there were drawbacks linked with them. Enemies could easily surround these castles. Cutting off vital supply lines to these castles meant certain doom for inhabitants.
One of the Middle Ages' most famous sieges occurred at Rochester Castle in 1215. The siege followed an incident where Archbishop Langton failed to hand over control of it to the Bishop of Winchester per King John’s orders. King John unleashed his trebuchets on the castle but they had little effect on the castle’s stone exterior. He had to undermine the castle walls in order to get inside. Undermining walls involves digging out the dirt beneath them, causing them to collapse under their own weight.
Sieges and undermining can destroy castles. Rochester Castle had been abused for hundreds of years and was slated to get demolished in the eighteenth century. Several individuals, including Edward III and Richard II have repaired and improved the castle since then. Such efforts have kept the castle standing.
This particular castle was not cheap to build. In total, Rochester Castle cost around $4,724 US Dollars (USD) to build. This was equivalent to around one-third of the king’s annual income at the time. In these times, laborers earned around about three cents per day.