The National Trust has objected to a farmer's plans for a 'super dairy' in Powys because it could spoil the view from a nearby castle.
It said Fraser Jones' proposal could have a "significant visual impact" on Powis Castle in Welshpool.
The building was designed to have a "commanding view over the Severn Valley", added the trust.
Mr Jones said other farm buildings and factories could already be seen from the castle.
Mr Jones intends to plant trees to screen the dairy in the village of Leighton, and he has employed an architect to illustrate what his building would look like from Powis Castle.
His milking parlour would be one of the first of its type in Wales and could house up to 1,000 cows. He claims it would improve milking conditions.
His proposal has received support, but it has also been criticised by some local people and animal welfare charity, Compassion in World Farming.
The National Trust, which runs Powis Castle, is now opposed to the development as well.
A spokesman said: "The National Trust has objected to the proposed development of a 'super dairy' at Lower Leighton Farm because of its potentially significant visual impact on the setting of the land and buildings in our care at Powis Castle.
"The castle and gardens were designed to have a commanding view over the Severn Valley at Welshpool - views that are enjoyed by some 110,000 visitors every year.
"Despite proposals to screen the new buildings with trees Powis Castle is in an elevated position and we do not believe this will reduce the visual impact to an acceptable level.
"Consequently we suggest that the development should be refused."
Mr Jones said: "I have employed an architect to draw an impression of what the building would look like from Powis Castle, close up and from a distance. It shows what the trees would look like from year one to year five. I am set to pass these details to the National Trust.
"I plan to plant trees to shade the development and that would be one of my first jobs.
"But various other farm buildings and factories can already be seen from Powis Castle and they've been there for years."
Powis Castle, which dates back to 1200, is regarded as one of the jewels in the National Trust's crown.
One of its guide books waxes lyrical about the castle grounds being "gardening on the grandest scale".
Powis's 300-year-old hanging terraces are renowned as some of the best surviving examples of baroque garden architecture in the UK.
It also has up to 3,000 plants, 300-year-old Yew trees, and it takes four gardeners three months to trim the hedges.