Protest over Caerphilly Mountain housing plans
About 400 people have attended a protest against plans to build hundreds of homes and a bypass at beauty spots in Caerphilly.
Campaigners say proposals for greenfield land on Caerphilly Mountain and other farmland and meadows around the town would ruin the environment.
They have been supported by wildlife expert Iolo Williams.
Caerphilly council is consulting on the plans and said housing was "much needed" in the area.
Under the proposals, up to 685 homes would be built on a 30-hectare (74-acre) plot of land on the lower slopes of the mountain.
Some of the homes would be built on a brownfield site - the former Ness Tar Plant - but others would be built on adjoining land at Nant-y-Calch farm.
The proposed bypass would link the Caerphilly Business Park roundabout to the A469 Caerphilly Mountain Road, which leads to Cardiff.
In addition, a further 900 homes and industrial sites would be built on greenfield land at Gwern y Domen and Plasnewydd Farm.
The development is part of wider plans to build about 4,000 new homes in the Caerphilly area over the next 15 years.
Kirsty Luff, who helped organise the protest at Twyn Community Centre in Caerphilly on Saturday, said she had been "amazed" by the numbers of people who attended.
"People are worried about the lack of infrastructure to support so many houses," she said.
"Caerphilly is already congested and the air quality is already really bad, so they are concerned this will make it worse," she said.
"We are also lucky to have things like barn owls and flower meadows here and we really should be making more use of these places rather than building houses on them.
"Yes, we need houses as we get a lot of overspill from Cardiff but we feel they should be built elsewhere rather than changing what makes Caerphilly distinctive."
TV presenter and wildlife expert Mr Williams said he was "horrified" to hear of the plans.
"Sites like these... are vitally important for nature conservation and local heritage as well as for local naturalists and walkers," he said.
"I am disgusted that they have been put forward for whole scale destruction and I will do everything in my power to fight this development."
In a report into the plans, Caerphilly council said: "The site can realise significant benefits in terms of providing housing and the first phase of the SE bypass and the remediation of one of the county borough's more contaminated sites.
"With careful and sensitive layout and design, the adverse impacts upon the landscape and ecology can be minimised."
It also said the site was in "the most attractive area to potential investors" in the county and the plan "allocates much needed housing in an area of acute housing need and housing pressure."