The impressive keep of the former fortress of Oberhofen was likely built in the early 13th Century.
In the 14th Century it belonged to the Habsburgs. After the Battle of Sempach, the Bernese troops occupied Oberhofen and soon afterwards the fortress and surrounding area came under the control of the Scharnachthal dynasty. Other Bernese dynasties followed. From 1652 to 1798, the castle became a bailiwick and was extended and converted into a castle. In 1801, it became a private property again. In the middle of the 19th Century, the castle was transformed under the Counts of Pourtalès whose ancestors had originated from Neuchâtel in Switzerland and migrated to Prussia.
In 1940, the American lawyer William Maul Measey established the Oberhofen Foundation. In 1954, the Museum opened to the public as an outpost of the Historic Museum of Berne. On January 1st 2009, Castle Oberhofen became an independent foundation again. In the new building on the seaside, which represents a bridge between the past and the 21st century, the Restaurant Schloss Oberhofen with its terrace on the lake opened in 2013.