Hundreds of people gathered in Frome to form a 'big hug' around a development site in the town.
The human chain was made in protest against an already approved housing project.
Campaigners are urging Mendip District Council to adopt their alternative plan for the Saxonvale site instead.
Mayday Saxonvale say their plans also include housing but would have more business space and a lido, and would better serve the community.
Paul Oster, Director of campaign group Mayday Saxonvale, said the big turnout for the event showed the level of support the alternative plan has.
He said: "It's just amazing. Loads of rain and still we filled the entire line all the way around the site, giving it a massive hug. Just astonishing.
"It's just really heartening, that level of support that's out there."
Among those who helped steward the event was local Mayor Andy Wrintmore, who said:
"We've all come out, we've all done something great together. I think it sends a very powerful message - 'this is what we want'.
"I think developers have to listen to what the town wants."