Selma Hall, also known as Kennett's Castle, was built by slaves on the Mississippi River bluff about 30 miles south of St. Louis in 1854. The owner and builder, Frederick Kennett, was a brother of former St. Louis mayor Luther Kennett and a friend of Thomas C. Reynolds. Kennett hosted Reynolds and newspaper editor Gratz Brown on the evening before their duel, which was held at dawn on Aug. 26, 1856, on a sand bar in the river just off Selma Landing. They didn't disclose the location prior to their duel, which violated Missouri law. Post-Dispatch file photo