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

In Martinszell, a district of the municipality of Waltenhofen in the Oberallgäu district, Bavaria, Germany, the Langenegg Ruin is located at approximately 753 meters above sea level. The former hilltop castle in the Allgäu stands on a wooded hill within a loop of the Iller River.
History+
Around 1250, the main tower of the complex was built, serving for centuries as the ancestral seat and center of power for three families. When the Lords of Langenegg died out in 1415, the castle passed to the Lords of Rauns. Later, they sold a part to the patrician Winter from Kempten, who subsequently also called himself von Langenegg. After the death of the last Lord of Langenegg in 1647, the castle fell into disrepair after reverting to the Prince-Abbot of Kempten, who did not maintain it.
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: 47.6153, 10.2936