A 70-metre glasshouse made of laminated larch and spanned by 21 timber arches, opened in 2003 as part of the Heart of the City regeneration. Over 2,500 plants from around the world thrive inside, from Norfolk Island pines and tree ferns to Mediterranean olives and Asian magnolias. The whole structure is so transparent it almost reads as a connecting passage between buildings rather than as an attraction in its own right.
Sheffield Town Hall is one minute's walk; the Millennium Gallery is connected directly through a glass walkway. Free entry, open every day. Sit in the café at one end with a coffee and a book on a wet afternoon — it is one of the best free public spaces in any English city.