The Palm House Kew Gardens

This original masterpiece from 1848 still surprises with its boldness. Very few large greenhouses had been built before and nothing as good has been built since. The architect was Decimus Burton, who had worked 5 years earlier to build the Great Conservatory at Chatsworth with Paxton, of Crystal Palace fame. The section of Chatsworth, curve starting at ground level surmounted by a second curve is repeated here, but Paxtons fussy herringbone glass framing is hugely simplified. This I think was the key contribution by the man who built it, Dubliner Richard Turner. He bought patent rolled wrought iron beams, intended for ship decking, in Millwall, shipped them to his works in Ballsbridge, Dublin and had them curved. The original glass was not only curved but specially tinted green with copper oxide to recreate the light of a tropical rain forest. The whole thing was technically very innovative, if not slightly courageous. The site was chosen by the patron of the whole enterprise, Director William Hooker, who also first opened Kew to the public. The relationship to the lake is sublime.
Burton was a big contributor to Regent Street and Regent's Park for which his father was the developer. He and Nash, the primary designer, didn't always get on. My favourite of his is the Athenaeum.