To be privately owned
Wohnturm Marsens (Puidoux)

The Marsens residential tower, a castle complex, stands in the Lavaux vineyard terraces in Puidoux, Canton of Vaud.
History+
The origins of the Marsens residential tower date back to the 13th century, when it was built by an unknown patron. As early as 1273, the property came into the possession of the Bishop of Lausanne. From 1287, the Francoz family were the owners, followed by the Counts of Gruyère, who owned the tower from 1356 to 1527. Subsequently, the Lords of Plait took over from 1527 to 1572, before the Clavel family of Cully and Ropraz acquired the rights. Although the Clavels retained the manorial rights, they sold the tower and the surrounding vineyards in 1870 to the Naef family.
Source: Wikipedia · Licence: CC BY-SA 4.0
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 46.4887, 6.7548