A 15th Century hall once owned by Henry VIII has opened its doors.
Apethorpe Hall was purchased by the government in 2004.
Work to rescue the dilapidated Grade I listed Apethorpe Hall has been carried out by English Heritage after it was labelled an "irreplaceable treasure".
The comment was made in 2004 by then Culture Secretary Tessa Jowell after the Northants site was recommended for compulsory purchase by the government.
Tours around the hall for visitors are being run by English Heritage, as it nears the completion of £4m repairs.
Apethorpe Hall and estate, dating from 1470, deteriorated after it was left empty since 1982.
The hall and outbuildings were classed Category A on the Buildings at Risk register, compiled by English Heritage in 1998.
English Heritage has been working to restore the site since it was purchased by the government in 2004, and aims to have the work completed by 2008.
Nick Hall, of English Heritage, said: "Once the first phase of this major repair programme is completed and the building is in a stable condition, it will be up for sale.
"We believe the best use for Apethorpe, a building which has suffered a very turbulent recent history, is the use for which it was always intended - a country home for a single, private owner."
The house opened over the summer, with up to 3,000 people visiting, English Heritage said, with tours continuing until 14 October.