Most London walking tours seem to deal with pubs, macabre histories of plague and murder or, more recently, Sherlock Holmesmania. So, I was glad to see this tour map highlighting some of the city's most important—and intriguing—scientific breakthroughs.
The map spans five centuries, including alchemy, Ben Franklin's lightning rod experiments, John Snow's investigation of cholera, and the spot where Leo Szilard is said to have conceived of the atomic bomb.
Even if you can't go on the tour yourself, the online interactive map is very well done. I hope to see it expanded to encompass even more material in the near future.
Visit the interactive tour of London's Greatest Scientific Experiments