A treetop sky-bridge, visitor centre and café have been given the go-ahead as part of contentious plans to develop Dublin's historic Hellfire Club forest lands into a major tourist attraction.
Local groups opposed to the scheme said they were devastated and angry by An Bord Pleanála's decision to approve the project, which aims to triple the number of visitors to the area annually.
They fear the development will damage the landscape and spoil its natural beauty while the influx of visitors will cause ongoing disturbance to local wildlife.
"We're shattered," said Elizabeth Davidson of Save The Hellfire. "There is so much opposition to this and we have been fighting it for four years but it seems we just haven't been heard."
South Dublin County Council is behind the development under an agreement with Coillte, which owns the land.
Hellfire Forest and Massy Wood cover most of the 152 hectares that lies in the foothills of the Dublin Mountains and commands spectacular views over the hills and city. Montpelier Hill at the highest point holds the remains of a hunting lodge built in the 1700s that became infamous for the antics of a wealthy social group who came to be known as the Hellfire Club.
The wider area has numerous other protected structures and architectural features as well as the remains of two passage tombs, and it is the home of red squirrel, merlin, pine marten and bats.
Central to the €20m development plan is a 1,000 square metre visitor centre incorporating a café, education centre and exhibition space, plus a treetop sky-bridge for walkers over the main access road, linking enhanced trails in the forests on either side.
Car parking is to be quadrupled to 275 individual spaces plus dedicated coach parking and the overall project is designed to boost visitor numbers from 100,000 a year to 300,000.
An oral planning hearing was held in 2018 and an initial inspector's report early last year recommended the project be refused permission unless much greater analysis was provided about the possible impact on wildlife.
An Bord Pleanála sought a number of additional assessments from South Dublin County Council and a fresh inspector's report found the concerns about wildlife had been addressed. The report recommended the project be approved apart from the sky-bridge.
It was considered likely to disturb wildlife and it was felt it would have to be enclosed for safety, which would make the structure too intrusive in appearance and scale.
An Bord Pleanála, however, has granted permission for all elements of the project, subject to a number of conditions including the drawing up of a forest management plan in conjunction with the National Parks and Wildlife Service and the appointment of an ecologist to oversee the works.
Opponents of the plan have the option of taking a court challenge but Ms Davidson said no decision could be made just yet.
"We have to read the inspector's report in detail and take expert advice," she said. "We're just trying to understand this decision. There are a lot of angry people."
South Dublin County Council has been contacted for comment.