High above the Amper River lies a mountain spur known as the Schlossberg (Castle Hill) or the Sunderburg, where evidence has been found of settlements from different eras. Excavations have shown that people lived here as early as the early Bronze Age (app. 1700-1600 BC). and there have been finds belonging to the Urnfield Culture (app. 1200-800 BC, and there are indeed grave mounds nearby.) In the Hallstadt Culture years the settlement was apparently abandoned. I have no knowledge as to whether the Romans used the hill for any strategic purpose, although it is rather close to the Via Julia, the roman salt road which ran from Salzburg to the Donau at Günzburg.
In the 11th century a fortress was allegedly erected on the hill by Count Friedrich of Diessen-Andechs, and Middle Age archaeological finds confirm this. The name Sunderburg was first mentioned in records in 1447. The House of Wittelsbach built a hunting lodge there in the 16th century.
On the steep slope to the river one finds mixed forest an, below that, rare flora in the wetland meadows downriver.
There is no information on hand about the earthwalls an the plateau, they could have been constructed in any of the periods where people used the hill.
An old local tale about the Sunderburg tells of it going under with all its inhabitants and treasures. A peasant, finding glass shards on the ground, took one home to find it had turned to gold. When he returned for more shards, they had all vanished. Another story tells of two pails of gold deep in the castle well, guarded by spirits which cannot be banished, which sinks further into the mountain every year. Similar stories of ancient gold in ancient fortresses can be found in Tirol, and probably wherever old, pre-christian settlements are known to have been. The locals may have known nothing of those prehistoric people, but the myths and legends often contain something of them.