13. The Palm House, Kew Gardens

Source: http://en.wikipedia.org/wiki/File:Kew_Gardens_Palm_House,_London_-_July_2009.jpg

Built by Decimus Burton in the 1840s, Kew Gardens' marvellous Palm House is believed by many to be 'the world's most important surviving Victorian glass and iron structure'.

14. The Temperate House, Kew Gardens

Source: http://en.wikipedia.org/wiki/Temperate_House

You don't have to look far at Kew Gardens to find astonishing Grade I listed buildings. The vast Temperate House is the largest surviving Victorian glasshouse in the world.