It's not every day a new park opens in the centre of a capital city, and this one is extra special. Copenhagen's new Opera Park is not just a nice place to relax in the shadow of the opera house. It represents a radical departure from the type of parks found elsewhere in the city: this harbourfront garden is a place for the contemplation of nature, of trees and plants from around the world, of water, and of sky. It's blessedly free from programming - there are no cycle paths, no running tracks, no outdoor gyms and no playgrounds.

For this episode we are lucky enough to be joined by its designer, Maj Wiwe, landscape director at Cobe. She explains the original idea behind the park, but also the extraordinary technical challenges involved in constructing a mature garden with 10 metre-high trees and a cafe. On top of a multi-storey car park. Which is buried underground. On reclaimed land. In the harbour. You see what we mean by challenges?