The Iron Curtain was an accidental wildlife haven. 30 years since the fall of the Berlin Wall, Tom Heap walks the borderlands to see how nature has continued to thrive.

Before the fall of the wall naturalists in West Germany had noticed that some bird and mammal species favoured life in the deathzone with its lack of human disturbance. When the Soviet bloc crumbled they joined friends and colleagues in the East to declare a Greenbelt through Europe, from Trieste on the Adriatic to Lubeck on the Baltic.

Against the odds their campaign has met with great success, creating new migration routes for some of Europe's biggest mammals whilst keeping developers away from most of the old border between East and West.

Producer: Alasdair Cross