Max Planck did his work in Berlin, Germany. He was a German theoretical physicist who is regarded as one of the most important physicists of the 20th century. Planck is best known for his development of quantum theory, which he first proposed in 1900. He also made important contributions to other areas of physics, including thermodynamics, optics, and statistical mechanics. Planck was a professor at the University of Berlin from 1892 until his retirement in 1928. He also served as the director of the Kaiser Wilhelm Institute for Physics from 1913 to 1933. Planck was awarded the Nobel Prize in Physics in 1918 for his work on quantum theory.