Crystal Palace Dinosaurs listed buildings from 1973, extensively restored in 2002, and upgraded to Grade I listed in 2007. The models represent fifteen genera of extinct animals, not all dinosaurs. They are from a wide range of geological ages, and include true dinosaurs, ichthyosaurs, and plesiosaurs mainly from the Mesozoic era, and some mammals from the more recent Cenozoic era. Following the closure of the Great Exhibition in October 1851, Joseph Paxton's Crystal Palace was bought and moved to Penge Place atop Sydenham Hill, South London by the newly formed Crystal Palace Company. The grounds that surrounded it were then extensively renovated and
Sir John Aird, 1st Baronet Aird & Co., in 1848. On his 18th birthday in 1851, Aird junior joined the family firm – which subsequently traded as "John Aird & Sons" for a while. The business had initially focused on gas and water network installations, but soon expanded into more general building work. John Aird's first significant scheme was the dismantling, transportation and re-erection of The Crystal Palace buildings from the 1851 Great Exhibition from central London's Hyde Park to Sydenham in south London. Other company projects included the construction of reservoirs and of railways and docks work. Aird became an associate of the Institution