The Brogyntyn Estate, on the edge of Oswestry, was once the seat of the Ormsby-Gore family.
Its most famous member was William David Ormsby-Gore, the fifth Baron Harlech, who was British Ambassador to America and a friend of President John F Kennedy.
But the current Lord Harlech sold the estate more than a decade ago after it had lain empty for 15 years.
Agent Knight Frank says the hall is being sold by the current owners, a private family.
On the market in 14 lots, it is described as "an important Shropshire seat in need of repair with extensive development potential".
The estate includes parkland, a walled garden and former terraced gardens, a stable block, a lodge cottage and a gardener's cottage. There is also a range of period farmbuildings, a former shooting lodge, two lakes and woodland and pastureland. There is even the remains of an iron age hill fort, and a 12th century fortress, Castell Brogyntyn, and views from the estate take in four counties.
Today Jonathan Bengough, from Knight Frank, said he was expecting interest from across the UK and beyond.
"The main hall is in need of refurbishment but there is extensive development potential."
The core of the main house, a grade II star-listed building, dates back to 1730 although a 1617 fireplace from the original building still remains.
The Harlech family moved out in the 1950s and the house was then let to British Telecom for an exchange.
"It retains its architectural glory but is sadly in need of a complete refurbishment," Mr Bengough added.
"Its sale presents an opportunity to restore it as an important country seat or for an imaginative re-development programme into several individual houses or alternative uses. It is easy to see and imagine the grandeur the house once held."