The Seizansō (西山荘), also known as the Nishiyama Goten (西山御殿) was the retirement villa of Tokugawa Mitsukuni, the second daimyō of Mito Domain under the Edo Period Tokugawa shogunate of Japan. It is located in the city of Hitachiōta, Ibaraki. The villa was designated a National Historic Site and its gardens a National Place of Scenic Beauty in 2007.