The remains of the Castle can be visited
Helmishofen Castle (Ruin)

The Helmishofen Ruin, also known as the “Roman Tower,” overlooks the Kaltental valley in the Bavarian Ostallgäu. This historic site owes its name to a 19th-century misunderstanding.
History+
Helmishofen Castle was built in the 12th century by the Lords of Helmishofen, who, as vassals of Kempten Abbey, held bailiwick and judicial rights in the region. Between 1190 and 1335, various members of this family were lords of the castle. The castle experienced several unsuccessful sieges by the Bavarians. After a fire in 1312, it was immediately rebuilt. In 1348, the castle was raided and plundered by Knight Swigger von Mindelberg, but the Abbot of Kempten rushed to its aid. From 1380 to 1437, the castle belonged to the Lords of Schmiechen, before passing into the possession of the Prince-Bishopric of Augsburg in 1437 and being administered by caretakers. During the German Peasants' War, the castle was plundered and partially destroyed, but the peasants had to assist in its reconstruction.
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: 47.9008, 10.7522