Listed in the National Register of Historic Places in 1966, the "Old City Hall" is now serving as the parish musuem. Built in 1848, the bulding served as the fourth courthouse for the Parish of Iberville. This grand Greek Revival building, plans of which were drawn by the famous New Orleans architect, James Gallier, is a single-story, brick and plaster structure which features four round Doric columns. They set off two huge cypress doors. Construction materials were indigenous to the area at the time, namely virgin cypress beans and wall boards along with three-foot-thick brick.

The building served as the parish seat of governmnet for 57 years until 1906, when a court house was built. The City of Plaquemine occupied the building as the City Hall until 1985. At that time it was recognized as the second-oldest structure in Louisiana still being used as a seat of local government. After several other occupants, the buildiing remained vacant for a number of years until retoration began in 1995. Over $200,000 was spent in restoration and now the building is serving the people of Iberville Parish for a third century as the Iberville Museum.