Available through MX Publishing, The London of Sherlock Holmes by Thomas Bruce Wheeler is a great resource, combining 21st century technology with the canon to provide a thorough piece of Sherlockian scholarship that you can sample via this online chapter.
On a superficial level, The London of Sherlock Holmes is an extremely fascinating book, providing a point-by-point analysis of locations disclosed within each story of the canon. (The online sample chapter focuses on "The Adventure of the Bruce-Partington Plans" [BRUC]"). For anyone considering a walking tour of Holmes' London, this would be more than adequate. However, reading the electronic version of the book via e-reader provides an additional level of engagement. Clicking on specific links automatically calls up Google Maps of each location. Combined with GPS maps, The London of Sherlock Holmes provides a much more immersive experience, bringing Holmes' London a little closer for readers.
Herewith a few examples of the interactive maps that Wheeler has created.
Famous Londoners' Blue Plaques:
Central London Pubs:
The London of Sherlock Holmes is a fascinating book that combines 19th century atmosphere with 21st Century technology to create a unique experience. This looks like a reference book well worth owning for any Sherlockian