Sebastopol House State Historic Structure is at the corner of West Court and North Erkel in Seguin in Guadalupe County. The structure, sometimes referred to as the Joseph Zorn House, was built in 1856–57 by Col. Joshua Wright Young, who named it for an important Russian naval base in the Crimean War. The house was later owned by Joseph Zorn, a local merchant and mayor of Seguin. Built in the Greek Revival Style, the house is particularly notable for its unusual construction, a concrete made from local gravel and lime poured into slip-form wall castings, a process developed and later patented by chemist John Esten Park, who lived in the Seguin area between the early 1840s and 1860. The house, one of only several surviving structures of some ninety built with the technique, was noted by Frederick Law Olmsted in his Journey Through Texas (1857). The structure was made a Registered Texas Historical Landmark in 1964 and added to the National Register of Historic Places in 1970. In 1976 the house and 2.2 acres were purchased by the state from the Seguin Conservation Society.