The public will be asked to vote for the winner after a television programme in early December.
Sustrans wants the funds for its national Connect2 project to create new walking and cycling routes for short journeys. John Grimshaw, chief executive of the charity, said: “Our projects are within a mile of as many as six million people, giving the £50m grant the power to make a massive difference to our health, environment and overall quality of life, today, tomorrow and for generations to come.”
The Eden Project hopes to launch an initiative called the Edge, aimed at helping communities to share their ideas for improving their lives and surroundings. Tim Smit, chief executive of the Eden Project, said: “For the nation and the world it would be a unique and powerful symbol that little old homo sapiens isn't prepared to walk passively through the gates of doom.”