The Kamerlingh Onnes Laboratory, which has produced so many Nobel laureates. For example, the physicists Hendrik Lorentz, Heike Kamerlingh Onnes, Pieter Zeeman and Johannes van der Waals. Leiden has produced many Nobel laureates but no institution has produced as many, and as significant ones, as the Kamerlingh Onnes Laboratory. The biographies of Lorentz, Kamerlingh Onnes, as well as that of the Ehrenfests, attest to the monumental significance of this laboratory for modern physics.