Plans have been unveiled to rebuild part of the walls of what is thought to have been one of England's largest medieval keeps.
Duffield Castle was destroyed by King Henry III in 1266 and all that remains today are its foundations.
The National Trust said it believes the Norman castle was the third biggest 13th-Century keep in the country.
Annice Fuller from DerwentWISE project, working alongside the trust, said the castle was of national importance.
She said the castle, which is barely visible from the roadside, has been "nearly forgotten about".
"It's a scheduled monument and it forms an integral part of the history of Duffield," she said.
The first stage of the project will see a clean-up of the site and new signage telling the story of the castle's history.
The castle, a few miles north of Derby, was destroyed when the Ferrers family rebelled against the king.
All that remains are a one-hectare site with foundations covered in tarmac and a stone-capped well.
Stones that are currently above ground were placed there by Victorian antiquarians, when the castle was re-discovered in 1886 but key parts were missed.