In 1863, Lord Takachika Mori moved the domain site from Hagi to Yamaguchi to take precaution against possible uprisings at the end of the Edo Period. A year later, in 1864, the Yamaguchi Oyakata or Yamaguchi Castle was constructed on the site. This modern western-style castle was a natural fortification surrounded by mountains, equipped with gun batteries, earthworks and water moats. The main gate of the domain's hall, moats and earthworks still remain.