Largest cast iron dome

The largest cast iron dome is the 44.2-m-diameter dome at the Devonshire Royal Hospital in Buxton, UK, constructed in 1881. Slightly larger than the famous Pantheon dome in Rome, at the time it was the largest unsupported dome in the world. The roof of the iron-framed dome is covered with slates, and topped by a circular lantern topped with small copper cupola.

Originally built as the servant quarters and stables of a large eighteenth-century hotel, the dome was added by architect Robert Rippon Duke as part of a conversion to a 300-bed hospital. After a £4.7-million restoration in 2003, the building is today part of the University of Derby.