Harperley camp won ancient monument status in 2002
A former Prisoner of War camp in County Durham which was advertised for sale online failed to attract any bids.
Tourist attraction Harperley camp, near Crook, was put on auction site eBay for £900,000 by its current owners who can no longer afford its restoration.
James and Lisa McLeod now hope a public body, charity or heritage organisation will step in to save the camp.
The camp housed German and Italian prisoners in World War II and won ancient monument status in 2002.
Mr McLeod said: "Unfortunately we have run out of money and can't take it any further. So we are in a stalemate situation."
Mr McLeod and his wife had hoped to turn the camp into a national visitor centre. They have spent about £1m on the 12-acre site over the past eight years, but had to mothball their venture two years ago through lack of funds.
The camp needs investment of at least another £1m to complete its restoration.
Mr McLeod said: "The camp is of national and international importance. It is more than just for the North East."
The camp hosts an original theatre built by the former inmates and huts containing prisoners' wall paintings.
It narrowly missed out on a £2m windfall when it was featured on the BBC's Restoration programme, but failed to gain enough public votes to win.