The remains of the Castle can be visited
Schopflen Castle

The Schopflen ruin is the medieval ruin of a moated castle in the municipality of Reichenau in the district of Konstanz in Baden-Württemberg.
The Schopflen castle ruin is located at the eastern end of the Lake Constance island of Reichenau. It lies at the western end and on the southern side of the Poplar Avenue (Pirminstrasse or state road L 221 Konstanz-Reichenau), which today borders the Reichenau causeway at an elevation of 397.4 meters, and thus about 2.5 meters higher than the water level of the Untersee (394.93 meters). It is separated from the island of Reichenau by the ten-meter-wide Bruckgraben, over which a bridge leads to the Reichenau causeway to the mainland. When the Reichenau causeway was built in 1838, the castle came to lie on it.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://de.wikipedia.org/wiki/Datei:Schopflen.jpg
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: 47.6864, 9.1004