RTÉ has been refused permission by An Bord Pleanála to retain a controversial fence around its transmitter on Mount Leinster.
The decision means the mountain top should once again be open to hill-walkers and environmentalists, who fought a 17-month campaign to have the two-metre high barbed-wire fence removed. Sheep farmers had also objected to the loss of about three-and-a-half acres of land in a common grazing area.
Permission to retain the fence, which was erected without planning permission, was refused last year by Carlow County Council, but the station appealed.
In its decision, An Bord Pleanála said the fence was within a proposed special area of conservation, designated "high amenity" and of "national interest" in the Carlow county development plan.
Because of its length and the extent of the area enclosed, the structure "would represent an unacceptable degree of injury to the amenities of the area and would, therefore, be contrary to the proper planning and development of the area".
The deputy leader of the Green Party and Carlow County councillor, Ms Mary White, who in August 2000 promised "the mother of all environmental fights" to have the fence removed, said the outcome was "a victory for democracy and the local environment".
"The hideously ugly chain link fence which many had regarded as an act of environmental barbarism by RTÉ will now have to be removed and the landscape restored to its former glory," she said.
An Taisce, the Tullow Mountaineering Club, the Friends of Mount Leinster, the Keep Ireland Open Campaign, farmers and local residents all took part in the campaign to have the fence removed.
RTÉ initially erected a 2.5-metre high fence, but reduced this to two metres, as a fence this height in a rural area is normally exempt from planning permission.
Carlow Co Council, however, said the exemption did not apply in cases where the land in question had been habitually open to the public for the previous 10 years.
The fence was necessary, RTÉ said, to protect both the public and the station's property.