Newcastle-based architects Jane Darbyshire and David Kendall’s (JDDK) long-touted Landscape Discovery Centre and Youth Hostel at Hadrian's Wall in England’s Northumberland National Park is set to be realised after contractors for the scheme agreed cost proposals, with development now underway.

The most recent plans for ‘The Sill’ were announced in October 2014, outlining that the project needed at least £11.2m (US$17.9m, €14.3m) to get it off the ground. A Heritage Lottery Fund (HLF) grant of £7.8m (US$11.8m, €10.4m) was awarded to the project in February, with the final figure agreed last week now standing at £14.8m (US$22.9m, €20.3m).

JDDK’s design incorporates the Northumbrian landscape in both its form and materials used in construction. A living grass roof, planted to replicate the surrounding natural grasslands, will gently ascend, offering views of the surrounding national park and the UNESCO World Heritage Site of Hadrian’s Wall, while locally-sourced materials are being used for the rest of the development. As part of the original design brief, JDDK have incorporated learning facilities, group-friendly accommodation, conference and exhibition spaces, retail amenities and a local produce café with communal spaces into the design.

The Sill is also designed to be eco-friendly, meeting the highest standards of sustainability, with a target of generating 80 per cent of energy consumed on-site.

The site, which sits on Hadrian’s Wall, will be completely redeveloped, with the existing visitor centre and youth hostel demolished, and the new development brought up in its place. The project is the first dedicated Landscape Discovery Centre in the UK, which will include learning, participation and research initiatives across the areas of heritage, landscape, conservation, countryside management, and leisure and tourism.

“The Sill represents the largest scale initiative of its kind in the history of not only Northumberland National Park Authority, but national parks across the UK,” said Tony Gates, chief executive of Northumberland National Park Authority.

Engineering and construction firm Sir Robert McAlpine are general contractors for the development, and will work alongside JDDK as well as planners Cundall, landscape architects Glen Kemp and project managers Gardiner and Theobold. The development is expected to take 18 months to complete from start to finish, with The Sill fully operational by Q3 2017.

“This is an important milestone for Northumberland, which will bring a host of benefits to the county, including significant opportunities for local businesses and rural enterprise while boosting our tourism offering,” said councillor Val Tyler, cabinet member for arts, leisure and culture at Northumberland County Council. “The Sill will play a key role in our economic growth strategy and I’m delighted to see that it has been given the go-ahead, bringing with it prosperity and jobs for the county and the North East.”

Once complete, it is hoped that The Sill will attract more than 100,000 visitors per annum. Work is set to start on the site later this week.