The rules of architecture have been discussed since the Roman architect and engineer Vitruvius coined the trilogy firmitas, utilitas and venustas, most commonly translated as firmness, commodity and delight. Put simply, this means that a building should stand up and endure, that it should serve its function, and that it should give pleasure to its users and the wider community. Great buildings, like great art, contain something that is impossible to define or pin down. But that greatness, in almost all cases, overlays the principles set out in this book. While one cannot guarantee that a building will be great, if all the principles are followed, you will avoid the pitfalls to which too many are subject.