A planned €19m welcome centre at the Hell Fire Club in the Dublin mountains must be "as sustainable as possible", it has been claimed.
South Dublin County Council has proposed a 72-seat cafe, toilets, changing facilities, a 'walkers' lounge', outdoor terraces and a shop at the centre.
In addition, there is expected to be an interactive education room.
The walking trails will be improved, a variety of trees will be planted, archaeological and historical sites will be protected and a larger car park is expected to be provided.
However, Green Party councillor and architect Francis Duffy is concerned about the sustainability of the project, as well as its location.
"I'd welcome something of that nature in the Dublin mountains," he said.
"I'm all in favour of that, I'm not 100pc sure of the siting of it.
"They're proposing to put a drainage line down the mountain which I don't think is a good idea, they should be able to contain the waste up there.
"If you're building a public building, a landmark building you should be trying to make it as sustainable as possible."
He said he has made several recommendations but feels they have been "brushed aside".
Independent councillor Deirdre O'Donovan wanted to dispel any negative myths about the development.
"I think there's been a lot of misinformation," she said.
"People were contacting me saying they don't want to have to pay to go to this incredible site that's free at the moment.
"And that was one of the assurances that we got at the briefing, which is that the only thing you will have to pay for is if you want to buy a cup of coffee in the 72-seater cafe - which is not a humongous monstrosity."
Cllr O'Donovan said the site has been "neglected", with people leaving broken bottles and rubbish behind.
"At the moment there's 100,000 visitors going up there, that's completely unmanaged and that's not sustainable," she added.
The council has applied for funding from Failte Ireland and a request has been put to An Bord Pleanala.
Keep Ireland Open chairman Roger Garland is extremely opposed to the development and intends to fight it.
"It's a very unique area and it should be left alone. The Hell Fire Club will be totally overwhelmed by the cafe," he said.