From the record
“Goldenrod was a floating theater, known as a showboat, which operated on the Mississippi River and its tributaries throughout the 20th Century. National Historic Landmark on 24 December 1967 and a St.”
Wikipedia article Goldenrod (showboat), CC BY-SA 4.0.
One of 3 National Register listings published here for Calhoun County · category: Structure · a National Historic Landmark.
Sources: the Wikipedia article · the National Register database, National Park Service