Kent has many castles for a few reasons. Firstly, Kent is located on the southeastern coast of England, which made it a prime location for invasion throughout history. This meant that castles were built as defensive structures to protect against foreign invaders.
Secondly, Kent has a long and rich history, with many different cultures and civilizations leaving their mark on the region. For example, the Romans occupied Kent and built fortifications there, and after them, the Saxons and Normans built castles in Kent. This long history of occupation and settlement has left behind a wealth of historic buildings, including castles.
Thirdly, Kent has many strategic locations, such as ports and river crossings, which have made it an important region throughout history. This has led to the construction of castles to control and protect these important sites.
Finally, Kent has a landscape that is well-suited for castle building, with many hills, valleys, and rivers that provided natural defenses and made it easier to build fortifications. All of these factors have contributed to the high number of castles in Kent.

- Canterbury Castle: Canterbury Castle is the oldest castle in Kent and was built in the 11th century, shortly after the Norman Conquest.
- Dover Castle: Dover Castle is a medieval castle that was built in the late 11th century by William the Conqueror to defend against invasion.
- Rochester Castle: Rochester Castle is a Norman castle that was built in the late 11th century by William the Conqueror to control the River Medway and to protect against attack from the east.
- Tonbridge Castle: Tonbridge Castle is a medieval castle that was built in the 11th century by Richard Fitz Gilbert, who was granted the land by William the Conqueror.
- Upnor Castle: Upnor Castle is an Elizabethan artillery fort that was built in 1559 to protect the River Medway from invasion.
- Westenhanger Castle: Westenhanger Castle is a medieval castle that was built in the 14th century.
- Scotney Castle: Scotney Castle is a ruined medieval castle that was built in the 14th century by Roger Ashburnham.
- Lullingstone Castle: Lullingstone Castle is a manor house that was built in the 15th century.
- Walmer Castle: Walmer Castle is a castle that was built in the 16th century by King Henry VIII as part of a series of coastal defences.
- Dover Western Heights: Dover Western Heights is a complex of fortifications that was built in the 18th and 19th centuries to protect the Dover area from invasion.
- Leeds Castle: Leeds Castle is a medieval castle that was built in the 12th century by Robert de Crevecoeur.
- Knole House: Knole House is a country house that was built in the 15th century.
- Allington Castle: Allington Castle is a medieval castle that was built in the 12th century by William de Cornhill.
- Hever Castle: Hever Castle is a castle that was built in the 13th century by William de Hever.
- Lympne Castle: Lympne Castle is a medieval castle that was built in the 13th century.
- Saltwood Castle: Saltwood Castle is a medieval castle that was built in the 12th century by Robert de Crevecoeur.
- Sissinghurst Castle: Sissinghurst Castle is a country house that was built in the 16th century.
- Queenborough Castle: Queenborough Castle is a medieval castle that was built in the 14th century by Edward III.
- Cooling Castle: Cooling Castle is a medieval castle that was built in the 14th century by John de Cobham.
- Chiddingstone Castle: Chiddingstone Castle is a country house that was built in the 16th century.
- Eynsford Castle: Eynsford Castle is a ruined Norman castle that was built in the 11th century.
- Hadlow Castle: Hadlow Castle is a country house that was built in the 19th century to resemble a medieval castle.
- Godinton House: Godinton House is a country house that was built in the 14th century.
- Newenden Castle: Newenden Castle is a ruined medieval castle that was built in the 12th century.
- Old Soar Manor: Old Soar Manor is a medieval manor house that was built in the 13th century