Barbican Conservatory

Six storeys above the stage of the Barbican Theatre, hidden inside one of the most brutalist buildings in London, there is a tropical rainforest. The Barbican Conservatory is the second-largest greenhouse in London after the Princess of Wales Conservatory at Kew, covering 23,000 square feet of lush, humid jungle perched on top of a concrete performing arts centre. It is, genuinely, one of the most surreal places in the city.

The conservatory was designed by the Barbican's original architects, Chamberlin, Powell and Bon, and wraps around the theatre's fly tower — the tall structure from which scenery is lowered onto the stage six storeys below. The plants were installed between 1980 and 1981, and the conservatory opened to the public in 1984. It now houses around 1,500 species of tropical plants and trees, some of which are rare and endangered in their native habitats.

The three pools inside are home to koi carp, ghost carp, and grass carp from Japan and America, along with cold-water fish like roach and rudd. A smaller pool provides a haven for rescue terrapins. The entire roof is steel and glass, beneath which sits over 1,600 cubic metres of soil — all of it hand-mixed to specific requirements and carried up into the building piece by piece.

The conservatory is only open on Sundays and selected bank holidays, which adds to its mystique. Most Londoners have never been inside, and those who have tend to describe it the same way: walking through a concrete corridor into sudden, overwhelming green, as though someone cut a hole in the Barbican and dropped in a piece of the Amazon.