Alt-Bichelsee Castle, castle ruin in Bichelsee-Balterswil, Thurgau, Switzerland

Alt-Bichelsee is a castle ruin located on a steep ridge above the village of Bichelsee in Thurgau. The remains show foundations, ditches, and terraced levels that show how the fortress once rose across several stories on different heights of the hillside.

The lords of Bichelsee, Walter I and Eberhard I, are first documented in 1209 as ministeriales of St. Gallen Abbey. In 1250 the family built Neu-Bichelsee Castle, not Alt-Bichelsee, and Eberhard I founded Tänikon Abbey. Alt-Bichelsee was sold in 1358 to Hermann IV von Landenberg-Greifensee, burned by Appenzell forces in 1407 and rebuilt, then sold in 1421 to Fischingen Abbey; it decayed and its last stones were used for the village church in 1864.

The ruins overlook the village of Bichelsee and mark where a local noble family once lived and held power over the region. Today you can still see how they controlled the area from this high point and how important the castle was to people living below.

The ruins are reachable by hiking trails that start from the village and lead through fields and woods up to the hilltop. Wear sturdy shoes for the steep final climb and uneven ground at the site.

The castle's last visible remains were quarried away in 1864 and reused to build the village church of Bichelsee. What visitors see today is therefore only the site itself: a rampart and ditch facing the village and a large ditch cutting off the main castle on the mountain side.