Mikhail Osipovich Eisenstein (Russian: Михаил Осипович Эйзенштейн, romanized: Michail Osipovič Ejzenštein, Latvian: Mihails Eizenšteins; 17 September [O.S. 5] 1867 – 2 July 1920) was a civil engineer and architect working in Riga, the present-day capital of Latvia, when the city was part of the Russian Empire. He was active as an architect in the city at a time of great economic expansion and consequent enlargement, which coincided with the flourishing of Art Nouveau architecture. During the years 1901–1906, Eisenstein designed many of the best-known Art Nouveau buildings of Riga. His son, Sergei Eisenstein, became a well-known Soviet film director.