Ambitious plans to create what would be the region's first five-star hotel alongside Europe's largest golf course have been submitted to planners.
Rockliffe Hall in Hurworth, near Darlington, owned by Middlesbrough Football Club, is the site for the development which aims to create one of the UK's finest country house hotels.
In January, the public was given its first sight of the multi-million pound plans to renovate the disused 19th Century hall into a luxury complex.
Now a formal planning application has been submitted to Darlington Council, which will launch a public consultation.
The 362-acre site will include a country house hotel and spa, a well-being centre, banqueting and conference halls, Turkish baths and three restaurants.
It will also boast what will be Europe's longest 18-hole championship golf course, with exclusive club house.
The proposal also includes plans for a residential development of 26 luxury houses within the estate at Rockliffe.
The cost of the project is believed to be around pounds 50m. The proposal has been put forward by development team Rockliffe Hall Developments, with Middlesbrough FC the driving force behind the enterprise.
Warwick Brindle, a spokesman for Rockliffe Hall Developments, said its vision was "to create the best country house hotel the UK has ever seen".
He said: "The development will represent a significant investment in the local economy as well as the creation of more jobs for the region."
Rockliffe Hall was built in 1863. It was originally owned by Alfred Backhouse, a member of the Darlington's famous banking family. During the Second World War, it was used by the military and was later sold to the Hospitaller Order of St John of God.
Middlesbrough FC bought the site in 1996 and started work on the pounds 7m training facilities two years later.
If planning is authorised, the development team hope to begin work on construction this summer with completion of Rockliffe Hall expected for opening in early 2009.