For all of the iconic buildings and locales that make up London there were many proposals and visions which went unrealized. Felix Barker and Ralph Hyde's book provides a fascinating account of the various plans made over the previous four centuries, many of which would have created a very different metropolis from the one that exists today. In the process, the authors shed light on an often-overlooked part of London's history, one that is enormously fun to read for the humor with which they address some of the more outlandish suggestions and the speculation it inspires for how very different the city might be had some of these projects ever been realized. ( )