Architecture was the structure of buildings, or the design and study thereof.
In the 2180s, in London, Alex Campbell studied architecture because he wanted to become an architect. He left for a grand tour of Europe to see the historical architectures left after the Dalek invasion. (AUDIO: Relative Dimensions)
On Kirith, the Seventh Doctor wonder what King Charles would have to say about the Council House's blend of architectural styles. (PROSE: Timewyrm: Apocalypse)
When on the Tick-Tock World, Barbara Wright noted the conflicting architectural of the many buildings. Ian Chesterton doubted the relevance of this, noting that even just walking down a London street would expose one to conflicting styles of architecture. (AUDIO: Tick-Tock World) When the two visited the Thal City, they noted its architectural similarities to the Dalek City. (AUDIO: Return to Skaro)
TARDISes had malleable architecture through their architectural reconfiguration system. (TV: Journey to the Centre of the TARDIS, AUDIO: Eye of Harmony) It was rumoured that the Capitol also employed this technology to constantly relocate the Celestial Intervention Agency's main office. (PROSE: A Brief History of Time Lords)
Anarchitects were conceptual entities which could inhabit architecture. (PROSE: Alien Bodies, The Book of the War)