The National Archives holds a large number of architectural drawings, particularly of public buildings and monuments. There are examples of almost every kind of building and structure erected during the 19th and 20th centuries, from official buildings such as the Houses of Parliament to railway stations, coastguard cottages and Crown Estate in central London.
There are also drawings of structures such as bridges, piers, statues and railway signal boxes. See the research guide Architectural Drawings in The National Archives.
The National Archives' image library has more images of buildings and plans.