An "eerie" underground bunker built during the Cold War has been put up for sale with a guide price of £25,000.
The former monitoring post near St Agnes, Cornwall was built in 1961 and is accessed down a 14ft (4.2m) ladder.
Sellers have suggested "a variety of uses" for the "out of the ordinary" property, subject to planning permission from Cornwall Council.
It was used in the Cold War to monitor aircraft and any potential nuclear threats, said auctioneer Adam Cook.
The bunker was manned by volunteers and consists of an access shaft, a toilet and a monitoring room.
It is being auctioned online as part of a triangular piece of land on 18 February.
The site was first opened in 1961 and closed in 1991 and is accessed down a "rustic vehicular track", according to the online advert.
Mr Cook said it is a former Royal Observer Corps Monitoring Post "but people love calling it a nuclear bunker".
He said the bunker would have been one of around 1,500 monitoring posts built in coastal regions in the UK between the 1960s and 1990s.
Accessed by a hatch, Mr Cook described the reinforced concrete bunker as "a little bit eerie when you're there on your own".
"I'm glad I've been down there...[to have] half a chance of explaining it to customers."
He said there was still a sense of what it used to be with an "old bunk bed" and a toilet "which I don't think you'd fancy using but it certainly gives you the atmosphere".
Mr Cook explained it is "difficult to pigeon hole it onto any one kind of purchaser" and said the buyer could be anyone from a history enthusiast to a landowner.
"All kinds could be interested and we're already getting lots of calls about it."