We will visit two remarkable villas, which are important pieces of Czech architecture of the 1930s. Villa Müller (1928–1930), authored by Adolf Loos, is the chef-d'oeuvre of the world's architectural avant-garde. Loos brings to perfection his original concept of space, the so-called Raumplan which is fully used in the villa. The interior design of the villa, chosen and in many cases designed by the architect himself, combines luxury with simplicity and functionality and confirms Müller's villa in the role of a unique work of modern architecture and design. The Rothmayer Villa (1928–1929) was built by the architect Otto Rothmayer. His life and work are connected with the personality of the Slovenian architect Josip Plečnik, with whom he collaborated mainly on the reconstruction of Prague Castle. The permanent exhibition and the beautiful garden of the villa recall the atmosphere of the house, as a unique intellectual and artistic background, which the Rothmayers created here.