A World War One fort in the Humber estuary, which has lain empty since the 1950s, has been sold for £117,000.
Haile Sand Fort, described by auctioneers as "utilitarian in design," was built between 1915 and 1918 to protect the estuary.
The building, off Grimsby, had a guide price of £90,000 for the auction.
Auctioneer Lucy Crapper, from Blundells, in Sheffield, previously said: "It is a unique property and there's so much scope with it."
The identity of the new buyers is not yet known.
Its previous owners, who live locally, had bought it a number of years ago, Ms Crapper said.
The offshore concrete building with steel armoured plating previously went on the market in 2016 with a price tag of £350,000.
During World War Two, Haile Sand Fort and the Bull Sand Fort, near Spurn Head, were attacked by German U-Boats and aircraft.
A steel mesh was stretched between the forts across the mouth of the estuary to prevent enemy submarines getting to the large ports Hull and Grimsby.