Peter Ackroyd enjoys a deserved reputation as the foremost contemporary interpretor and historian of London, especially the city's hidden and arcane aspects. As a painter of London's underbelly he is unquestionably Dickens's heir. His feeling for the city as an almost living entity, oppressive in the accumulated weight of its sprawling physical structure and the mass of lives that have passed through it, and frequently been crushed in the process, is one shared probably more or less conciously by most Londoners. In such an environment, where the most modern buildings can stand on a street pattern centuries old, the present can never entirely cut itself free from the past. This is Ackroyd's main theme, brought to life with chilling brilliance in this story of murder and superstition in the 17th century sounding a physical echo in a series of slayings in the 20th. Be aware that this is not a simple murder mystery in period costume. The narrative is poetic and allusive with much, especially the ending, left for the reader to interpret. It is not wholly succesful in the intertwining of past and present. Ackroyd's 16th century London fizzes with life, the characters and the city brilliantly conjured (Ackroyd has a skilful ability to write in a way that is actually less archaic than it feels when caught up in the narrative flow). By contrast, he fails to breathe much life into the modern day scenes and characters. This may be partly an intentional contrast, but either way these scenes are rather flat. Nonetheless, the book is hugely enjoyable. The demonical architect Nicholas Dyer (the 20th c. detective is the Hawksmoor of the title) is a great creation, and the dark world he inhabits stands with the classics of the literature of the macabre and supernatural. It will certainly impell a London (or London bound) reader to explore the churches built by the historical Hawksmoor with new eyes, as however fantastical the story, the geography and architectural details are completely accurate. I remember well seeing tramps descend into the shelter in the understory of Christchurch Spitalfields.
The structurally flawless (and very chilling) 'Dan Leno and the Limehouse Golem', which inhabits the London of Jack the Ripper and the heyday of the Music Hall, is also highly recommended.