Barbican Conservatory London

The definition of a concrete jungle, this glass-topped conservatory is a surprisingly lush urban rainforest inside the brutalist Barbican, London’s second-largest after Kew Gardens. More than 2000 species of plants, along with fish, birds and terrapins, reside in this space, originally designed to hide the theatre's six-storey-high rigging system. Check the website for dates of gardener-led tours (adult/child £12.50/10) and afternoon teas (£35).