Altentann Castle

The former moated castle Altentann, as well as the castle ruin Lichtentann, also located in today's municipality of Henndorf, were built by the Lords of Tann. The County of Henndorf was originally a fief of the Bavarian Dukes. During the turbulent period of the Interregnum, Eckhart VI of Tann began building Lichtentann Castle around 1225 without the permission of the Archbishop. In 1272, he had to hand over the castle to Archbishop Friedrich II of Walchen for five years. Although his son Eckhart VII of Tann was obliged in 1314 to stop further expansion of Lichtentann, the castle complex was completed.

After the death of Eckhart XI, Archbishop Ortolf von Weißenbeck, supported by a feudal confession from 1302, seized Lichtentann Castle as "escheated fiefs". Eckhart X of Altentann received the castle as compensation for life. After the death of Eckhart X in 1355, Archbishop Ortolf wanted to access his estates. However, the deceased's son, Eckhart XII, allied himself with Duke Stefan II of Lower Bavaria, leading to the great "Tann Feud" against the Archbishop. According to an arbitration award by Duke Rudolf IV of Austria, Eckhart XI had to cede the castle to the Archbishop. After a settlement with Archbishop Pilgrim II of Puchheim, he once again received Altentann Castle and the court as a fief, but had to definitively renounce Lichtentann in 1369. After his death in 1391, the Archbishop seized all Tann possessions.

The Tann castles became the seat of administrators (Pfleger) who managed the courts of Lichtentann-Köstendorf and Altentann-Seekirchen. In 1607, the administration of Lichtentann and the court of Köstendorf were merged with the administration of Altentann. After the fire at Altentann Castle in 1680, the administrator moved to a separate courthouse in Neumarkt. The castle was left to decay. In 1809, the brewery owner Kaspar Moser from Henndorf acquired both castles or ruins. In the 18th and 19th centuries, they had only served as a quarry.