Buyers are being sought for two disused former nuclear bunkers, which are to be the stars of an unusual auction.
Each bunker was designed to house a three-man monitoring team
The bunkers, in Hawkshead, Cumbria, and Stannington, Northumberland are expected to fetch several thousand pounds each.
The former Royal Observation Corps bunkers were bought up by a telecoms firm as phone mast sites.
But after failing to win planning permission they will now be included in a property auction later this month.
Last year another disused bunker at Flookburgh in the Lake District, was sold for £25,100 on an online auction site.
The latest auction is being held in Lincoln on 18 November.
The Stannington bunker is sited north of Newcastle
Chartered surveyors JH Walter expect both bunkers to attract a lot of interest.
Spokesman Rob Ward said: "They are both in wonderful areas of the country.
"We are expecting a lot of interest.
"We actually had a deposit placed on the Hawkshead bunker, but we never heard anything again from the prospective purchaser, so it's up for sale again."
Each bunker was designed to house a three-man monitoring team 15ft underground.
The sites - which have no gas, electricity or water - are being tipped as the latest must-have investment opportunity.
The bunkers, decommissioned at the end of the Cold War, are all set in land 15 yards by 20 yards, with a ventilator shaft and an access shaft leading to two rooms - one housing beds, desks and equipment, and the other a toilet.