Plaque: 221b Sherlock Holmes
221b Sherlock Holmes, consulting detective, 1881 - 1904.
Site: 221b Sherlock Holmes (1 memorial)
NW1, Baker Street, Sherlock Holmes Museum, 239
Note that the real address of '221b' is 239, but the tourists don't seem to mind. 221b would actually be located where the Abbey National HQ used to be, the office block with the magnificent art deco tower, closer to Baker Street Station.
The Great Wen has done an interesting post about this museum and also the Festival of Britain Sherlock Holmes exhibition that was displayed at Abbey House (the art deco building) and was then moved to a pub in Northumberland Street where it is still (2014) on display.