St. Louis Plantation, plantation in Iberville Parish, Louisiana

St. Louis Plantation is a two-story Greek Revival house with Italianate touches located in Iberville Parish, Louisiana, built on a brick basement across 18 acres near the Mississippi River. The structure features round and square columns, Italian marble mantels, ornate plaster ceiling medallions, and a widow's walk with turned balusters overlooking the river and levee.

The original mansion called Erwin's Castle was built in 1808 by Jos. Erwin from Nashville but was destroyed by flooding in the early 1850s. The current house was constructed in 1858 at the same location by Edward James Gay, who later served as a congressman and ancestor of a US senator.

The house takes its name from the St. Louis Plantation, and its 1858 rebuilding by Edward J. Gay tied the property to a family active in Louisiana politics; Gay later sat in Congress. Visitors can read the two-story clapboarded frame cottage, set on a brick basement, as an example of Greek Revival and Italianate tastes in Iberville Parish. The site was listed on the National Register of Historic Places on December 3, 1975.

The plantation is in Iberville Parish, Louisiana, not in Baton Rouge; the nearest large city is Baton Rouge, reached by road via Interstate 10 and Louisiana Highway 75. The mansion is a private property, so visits depend on the owner's permission, and the grounds are rural with no marked visitor trails. The house was listed on the National Register of Historic Places on December 3, 1975.

The house still contains original kitchen fixtures from around 1865, including a brick hearth and wood stove, along with a fascinating early intercom system made of zinc tubing and megaphones for calling servants. Additionally, a large ornate mirror in the entrance hall may have come from a Mississippi riverboat and was part of a pair originally supplied together.