The 20th century has been called "The Century of Physics". It might be even more appropriate to call it "The Century of Solid State Physics". All the technological developments which changed the world by the end of the century were based upon previous scientific developments in solid state physics. The Braggs, Peter Debye, John Bardeen and L.D. Landau were certainly at the forefront of all those revolutionary changes, and they all feature in this examination of the great solid state physicists of the 20th century.