Berwick's town walls are its most famous piece of architecture and still stand strong today, hundreds of years after they were built.
Berwick actually has two sets of walls, the first - of which only fragments now remain - was built by Edward II, and was two and a half miles long.
The second set of walls is a mile and three-quarter in length. The ramparts completely surround the town, and there are only four gates through the walls.
Berwick's wall is now the only intact Elizabethan town wall remaining in England and when it was built in 1558 - designed to keep out the marauding Scots who regularly laid claim to the town - it was the most expensive undertaking of England's golden age.
The walls were built to an Italian design and contained bastions which were designed to give fire cover for every part of the wall.
Outside the curtain wall, as well as round the bastions, there were wide ditches kept full of water in order to deter potential invaders.
Walking around the town walls takes about 45 minutes and is a great way to witness Berwick's turbulent history at first hand. You can also take in stunning views over the town and look out towards the wide sandy beaches of the North Sea and the Tweed estuary with its colony of mute swans.
The castle and ramparts are open all year round - entry is free.