Chester Thordarson's boathouse on Rock Island State Park, WI. In 1910 wealthy inventor Chester Thordarson purchased 775 acres of Rock Island. 30 acres on the southwest side of the island were cleared in 1920 and Thordarson began construction of a summer estate. His large boathouse, which is decorated in with characters from the Norse Runic alphabet, is open to the public. It is an extremely well preserved piece of Wisconsin architectural history. The boat docking area under the building is actually used by overnight campers.