Many railways in London were built on viaducts composed of a succession of brick arches. The space under these arches has been used for almost everything any other building could be used for, from residential accommodation to aircraft manufacture.
In 2019, Network Rail sold its portfolio of railway arch properties to Telereal Trillium and Blackstone Property Partners, together trading as The Arch Company.[1] A tenants' organisation, Guardians of the Arches, was formed to coordinate responses to this.[2]