The composite nature of architecture is examined through diverse examples drawn from different periods and locations around the world. It is drawn from vernacular architecture and the hybridization of imported and local forms, through to urban typologies like the 'colonial city'. This leads on to an exposition of related theories of combinatorial innovation and design, from the 'metaphorical' theories of creativity advanced by several writers, to Brian Arthur's combinatorial theory of technological evolution, supported by his own and other examples. Taking a prominent feature of modern cities, the chapter concludes by looking at the evolution of the tower type and other new forms of high-rise architecture. While natural selection cannot explain radical innovations, Arthur does allow some kind of selective process to take place after the new technology comes into being.