The Museum für Moderne Kunst, or short MMK, in Frankfurt, was founded in 1981 and opened to the public 6 June 1991. The museum was designed by the Viennese architect Hans Hollein. Because of its triangular shape, it is popularly called "piece of cake". Since 2018, Susanne Pfeffer has been director of the MMK.

Hans Hollein was an Austrian architect and designer and key figure of postmodern architecture. Some of his most notable works are the Haas House and the Albertina extension in the inner city of Vienna.