Pontefract Castle has finally been removed from the ‘at risk’ register after 16 years.
The castle was deemed to be at risk in 2003 due to the poor condition of the ruins.
The council has since spent a decade delivering the £5 million Key to the North project.
Funded by the National Lottery Heritage Fund, Historic England and the Council, the project stabilised structures, opened areas not seen in hundreds of year and conserved and protected the ruins of the monument.
Extensive conservation work to the monument across the site, including the removal of masses of vegetation, which has revealed much more of the castle ruins than previously.
It has opened up the previously inaccessible area of the Sally Port, laid new paths and viewing platform at the Swillington Tower, built a new bandstand and built the new visitor centre includes an activity zone, museum displays, café, toilets and shop.
Neil Redfern, principal inspector of Ancient Monuments at Historic England, said: “It has been a long journey getting Pontefract Castle off the Heritage at Risk Register but has been well worth the effort.
“In recent years there has been a huge collective effort to make the site not only safe and structurally sound but to transform it into a well-used space that is at the very heart of the local community.”
Coun Denise Jeffery, new leader of Wakefield Council, said: “This is a testament to all the work that has taken place by the council and its partners.”