From ancient Rome onwards our civilisation has been built on concrete. It's incredibly useful but emits huge quantities of carbon dioxide in its production. What are the alternatives? Tom Heap and Helen Czerski explore the issues with a panel of experts: Professor Colin Hills from Greenwich University, Smith Mordak Chief Executive of UK Green Building Council, and structural engineer Roma Agrawal, who worked on the construction of London's tallest building, the Shard.

Producer: Emma Campbell

Assistant Producer: Toby Field

Researcher: Harrison Jones

Rare Earth is produced in association with the Open University