Dunstanburgh Castle was built in the centre of a designed medieval landscape, surrounded by three artificial lakes called meres covering a total of . The curtain walls enclose , making it the largest castle in Northumberland. The most prominent part of the castle is the Great Gatehouse, a massive three-storey fortification, considered by historians Alastair Oswald and Jeremy Ashbee to be "one of the most imposing structures in any English castle". Multiple rectangular towers protect the walls, including the Lilburn Tower, which looks out towards Bamburgh Castle, and the Egyncleugh Tower, positioned above Queen Margaret's Cove. Three internal complexes of buildings, now ruined, supported the earl's household, the castle constable's household and the running of the surrounding estates. A harbour was built to the south-east of the castle, of which only a stone quay survives. The site of Dunstanburgh Castle in north-east Northumberland was probably first occupied in prehistoric times. A promontory fort with earthwork defences was built on the same location at the end of the Iron Age, possibly being occupied from the 3rd century BC into the Roman period. By the 14th century, the defences had been long abandoned, and the land was being used for arable crops. Dunstanburgh formed part of the barony of Embleton, a village that lies inland to the west, traditionally owned by the earls of Lancaster. The origins and the earliest appearance of the name "Dunstanburgh" are uncertain. Versions of the name, "Dunstanesburghe" and "Donstanburgh" were in use by the time of the castle's construction, however, and Dunstanburgh may stem from a combination of the name of the local village of Dunstan, and the Old English word "burh", meaning fortress. Dunstanburgh Castle was constructed by Thomas, the Earl of Lancaster, between 1313 and 1322. Thomas was an immensely powerful English baron, the second richest man in England after the King, with major land holdings across the kingdom. He had a turbulent relationship with his cousin, King Edward II, and had been a ringleader in the capture and killing of Edward's royal favourite, Piers Gaveston, in 1312. It is uncertain exactly why Thomas decided to build Dunstanburgh. Although it was located on a strong defensive site, it was some distance from the local settlements and other strategic sites of value. Thomas held some lands in Northumberland, but they were insignificant in comparison to his other estates in the Midlands and Yorkshire, and until 1313 he had paid them little attention.