'Forgotten' castle brought to life with AR

Historians have recreated Plymouth's early defences using augmented reality (AR).

Peter Holt from the Ships Project has spent two years researching the story of the fort and castle, which once protected the Barbican and harbour in the 1300s.

Using old maps, documents and knowledge of architecture at the time, geospatial historian Chris Harvey created computer models and images of the two structures using AR, which overlays computer-generated images onto real ones.

Mr Holt said the illustrations brought to life buildings whose history had been "forgotten".

Peter Holt is a historian and author at the Ships Project

The defences were constructed around the time of the Hundred Years' War to protect the prosperous port from French invaders, he said.

The historian has just written a book called Plymouth Castle and Barbican Rediscovered as part of his research.

He said: "Because many of Plymouth's records are missing, so much of the early history of Plymouth is gone.

"Uncovering that and telling that story to the people of Plymouth, gives Plymouth more a sense of place.

"It didn't all start with the Mayflower. Plymouth is really old."

The tower overlooked the harbour entrance, protecting the port which had become wealthy trading wine, wool and fish, Mr Holt said.

"We don't know when the first defences were built, but an old document mentions that it was sometime between 1272 and 1307.

"The first mention of a castle was in 1312, but this was probably referring to the smaller Barbican Fort."

This AR image of the fort by Chris Harvey shows the large chain boom that would be hoisted up when under attack to stop ships entering the harbour

He added: "The people of Plymouth were worried the French would come over, raid the place, bring ships, come into Sutton Harbour and take anything they wanted. And they did.

"This started in the 1300s and they came in and set fire to Plymouth about four times. So they had to start building defences.

"First they built the Barbican, chain boom, and fort to defend it."

Mr Holt said with so few records or drawings, it was documentation relating to the purchase of a ship's mast and a chain that had helped to form a picture of what the city's early defences had looked like.

Mr Harvey specialises in recreating the past using augmented reality and has produced three-dimensional computer images of some of the city's lost buildings.

He said: "it's an untold piece of Plymouth history really.

"It's very exciting, especially when you find clues and things just line up.

"If you are there today down on the Barbican looking up you can see the edges of the castle and the walls."