Be careful not to mix the National Portrait Gallery with the National Gallery. This museum (National Portrait Gallery) gives home to the largest portrait gallery in the world. Drawings, paintings and caricatures made between the medieval time and all the way to the present can be seen here. You can for example see portraits of Queen Elisabeth, Henrik VII, the members of the Beatles and much more.
Useful information about the National Portrait Gallery
Entrance: Free
Opening times: 10.00-18.00
Transport: Bakerloo (Northern line), Charing Cross (Bakerloo/Picadilly line)
Homepage: http://www.npg.org.uk/