A 43ha Merseyside coal mine, closed and partially derelict for 20 years, is to be transformed into a vast landscaped area with lagoons.
The Land Trust launched an international design competition two weeks ago to turn Cronton Colliery in Knowsley, Merseyside, into a visitor destination and public open space.
"We believe that the open spaces can be the catalyst for change for more than just the environment," said Land Trust chief executive Euan Hall. "The colliery has potential to become magnificent."
He said the trust wanted to identify a multidisciplinary team that could "demonstrate an empathy and understanding of the site".
Coal has been dug in the area since the 1500s but the first mine shaft was sunk in 1918. Mining halted 70 years later and the Land Trust took over ownership from the Northwest Development Agency in 2010.
Competitions consultant Joanne Wallis said: "Apart from a little woodland and three chimneys, the site is bare. Land Trust wants the land to self-generate income so this could mean an eco-hotel, visitor centre or some other form of architecture.
"Landscape will play a large part, with more woodlands and paths, green gyms, BMX parks, ranger services and camping. Dates depend on the planning application and entrants must come up with funding strategies."
The first deadline for the two-stage competition is 15 February and a winner will be announced in late March.
See www.thelandtrust.org.uk/community or www.architecture.com/competitions.
43ha - Size of the site to be redeveloped at the former Cronton Colliery on Merseyside.