The BAE Systems Maritime – Submarines shipyard at Barrow is the largest in the UK by workforce ahead of BAE Systems Maritime – Naval Ships in Govan. It was expanded in 1986 by construction of a new covered assembly facility, the Devonshire Dock Hall (DDH), completed by Alfred McAlpine, on land that was created by infilling part of the Devonshire Dock with 2.4 million tonnes of sand pumped from nearby Roosecote Sands. DDH is the tallest building in Cumbria at 51 m. With a length of , width of and an area of it is one of the largest shipbuilding construction complex of its kind in Europe.