Transport charity Sustrans' Connect 2 project and the Black Country Urban Park are among those on the short list for funding from the National Lottery People's Millions fund.
Other projects on the list include a plan to build a new visitor centre in Sherwood Forest and expand the woodland by 300ha, and a new Climate Change centre for the Eden Project.
Every night this week ITV has been screening a 15 minute documentary on each of the projects. A summary on all four will be shown tonight. Votes can be cast online here or by phone.
One of the key elements of the Black Country Urban Park involves the stabilisation of limestone workings under Dudley. They are being refurbished to form one of Europe's largest underground attractions.
ICE past vice president Professor John Burland, whose previous works include the stabilisation of the Tower of Pisa, has spent the past few months working with Dudley Council on the plans.
Visitors would travel by narrow boat on a canal once used by miners, which runs through the underground caverns. If the project fails to win funding, the mines may need to be filled in to ensure their long term stability.
"If we don’t do something now we could lose them forever," said Dudley Council project manager Penny Russell.
Sustrans chief executive John Grimshaw said: "We have created a sedentary lifestyle which makes people obese. The challenge now
is how we re-engineer it so that activity is built back into it."
Sustrans' nationwide Connect 2 project promises to revitalise Britain's engineering heritage by restoring and renewing disused viaducts. These include structures on the Crab and Winkle line between Canterbury and Whitstable which has connections to Telford, Stephenson and Brunel. Another is the Brunel swivel bridge in Bristol.
Fifty-eight new bridges would be built as part of the project and six existing viaducts would be restored. New walking and cycling routes for 79 communities would be created.
■ The winner of the £50M grant will be announced soon on ITV.