Not all of the castles in Pembrokeshire were built by the Normans after their invasion in 1066, as some were built by the Welsh in response to the actual event. However, it was the actual arrival of the Normans in the county in 1093 that castle building began in earnest. It was at this time that Arnulf de Montgomery, an Anglo Norman aristocrat, founded Pembroke Castle, which later grew into the seat of the earldom of Pembroke.

Welsh reaction to the invasion held the Normans for the next few years, but in the 12th Century, what became the county of Pembrokeshire saw a spate of castle building by the Normans.

Initially, these castles were earth and timber structures, mostly of motte and bailey design. Within 50 years of their arrival, a line of such castles had been built on the southern side of the Preseli hills that was to become the Landsker line, with a second phase of castles to the north of the Preselis.

In time these earthwork castles were replaced or integrated by stonework castles. However, the remains of approximately 20 of these earthworks can be found in the county, and a brief history of each can be found by following the menu to the right.

While the great stonework castle at Pembroke is a main focus of this section, the county has an enviable heritage of still standing, stone castles. Picturesque Manorbier on the south coast, the towering remains of Haverfordwest castle, Cilgerran castle in the far north of the county and the much upgraded Carew castle to name but a few. Virtual tours of some of these historic sites can also be found by following the navigation to the right.

Also to be found in this section is a history of the later forts built in the county during the 19th century in response to the threat of French invasion.