The Row House in Sumiyoshi (1976) by Japanese autodidact architect Tadao Ando. This is one of his first houses he built and is part of his best designs. It has been a great influence during my first years of architecture school. I like its radical denial of the chaotic context in favor of a secluded place for withdrawal and personal life and its uncompromising interior layout (to get from one room to another one has to cross an outdoor space, no matter what weather). Truly a masterpiece.