The lime tree is thought to be between 800 and 900 years old
Pitchford tree house is certainly one of the oldest, if not the oldest tree house in the world.
It was built by Shrewsbury wool merchants, the Ottley family, who bought Pitchford Hall in 1473.
It is not known exactly when the tree house was constructed, but, according to John Yates from English Heritage, it is at least 300 years old.
Its most famous visitor is said to have been Queen Victoria, who visited Pitchford as a 13-year-old princess.
According to John Yates from English Heritage the future monarch described Pitchford Hall itself as, "a very big cottage". Today the building is considered to be one of the finest timber-framed buildings in the country.
From the outside, the tree house looks like a miniature replica of Pitchford Hall. But John Yates said it had not always been like that.
"It started out with render all over it, to look like a stone building perched in the tree, so it would have been even stranger then," he said.
The tree house has been renovated at various times throughout its history, but in July 2010 English Heritage placed the building on its At Risk Register. John Yates said it was because the steps to the tree house were in a state of disrepair.
What English Heritage hadn't realised was that joint-owner Michael Ashmore had deliberately taken the steps out to prevent people trespassing on his land and possibly getting hurt.
Owner Michael Ashmore removed the steps to prevent trespassers
Mr Yates said: "The steps, which are vital to maintaining it, are in an incomplete and terrible state. That's one of the reasons why we regard it as at risk."
Mr Ashmore, who maintains the tree house himself, does not regard the steps as part of it. Even so, he has agreed to put them back.
In reply, John Yates said English Heritage would consider removing the tree house from its At Risk Register, once it had been checked.
It may turn out however, that a bigger risk to the tree house could be the tree in which it sits. Owner Michael Ashmore recently had it carbon-dated by an expert from Kew Gardens, who thought it could be up to 900 years old. Lime trees normally only live for about 400 years.
The tree house is now almost entirely supported by metal struts and Mr Ashmore has secured the tree branches with wires to prevent as much movement as possible.
No public access is allowed to Pitchford Hall and its tree house
Pitchford Hall used to be open to the public, and grants from the council and English Heritage helped pay to restore the house and its tree house.
But public access and public money stopped in 1992, when Mr Ashmore bought the property. And he is adamant that, because of the sensitive nature of his horse breeding business, the hall and tree house will remain private.
John Yates said Mr Ashmore was perfectly entitled to keep it private, adding that: "Obviously it's a pity that there isn't any public access to it... Pitchford is a sleeping beauty of Shropshire and one day it'll wake up again."