Google indoor maps

Google maps is starting to be helpful getting around indoors in some major buildings.
The selection is limited but growing. Some British indoor maps, places you might find a genealogist in London, are the British Museum, Museum of London, National Maritime Museum, National Portrait Gallery, and the Victoria and Albert Museum.
There are also maps of train stations and airports, although not Heathrow.
To view the indoor maps select the building and zoom in until the floor plan appears.