Wynnewood State Historic Area, also known as Castalian Springs, and located in Castalian Springs, Sumner County, Tennessee, includes the largest existing log structure in Tennessee. It is a National Historic Landmark.
The main building was built in 1828 by A. R. Wynne, William Cage, and Stephen Roberts, to serve as a stagecoach inn for travelers between Nashville and Knoxville. In 1834, Wynne purchased his partners' shares in the property and moved into the inn with his family, where he resided until his death in 1893.
A grouping of six log buildings, the main one and five dependencies, was listed on the National Register of Historic Places in 1971. It was further declared a National Historic Landmark, later in 1971.
The main building is 110 feet long and 22 feet wide.
It is open to the public and tours are available.
On February 5, 2008, during the 2008 Super Tuesday tornado outbreak, Wynnewood suffered major damage to parts of the second story, roof, and trees on the property.