Auenstein is located at the edge of the Auenklamm near the hamlet of Au in the outer Ötztal valley. In the High Middle Ages, the castle secured a busy transit route leading from the Ötztal via Kühtai to Sellrain, and further over Axams into the Inn Valley.
The site is mentioned only once in historical records: in 1259 it appears in a document as “antiquum locum munitionis super fluvio Ez”—“an old fortified place” above the Ötztaler Ache river. At that time, Berthold of Neiffen donated the castle—together with estates inherited through his wife Ita of Marstetten—to the Prince-Bishopric of Brixen and its bishop Bruno of Kirchberg. Bruno was in conflict with the powerful Hohenstaufen dynasty over nearby Petersberg Castle near Silz. Acquiring as many estates as possible around this central stronghold in the Inn Valley was intended to strengthen his position. Although Auenstein itself played only a minor role in these disputes, it still held significance within the wider network of regional power.
During the High Middle Ages, political authority in Vinschgau, the Upper Inn Valley, and the Ötztal was initially held by the Welfs. On the ground, however, power was exercised by loyal families—most notably the Lords of Ronsberg from the Allgäu, who became the dominant political force in the Upper Inn Valley. In the Ötztal they also acted as bailiffs for the Bavarian monasteries of Ottobeuren and Frauenchiemsee, both of which owned large estates here. Through settlement and land clearing, their economic and political influence continued to grow.
Around 1200, the Ronsbergs built Auenstein Castle on one of the main transit routes, a clear sign of their power, which peaked at the end of the 12th century. But in 1212 the male line of the family died out. Their inheritance passed to three daughters and their husbands: Ulrich of Eppan-Ulten, Heinrich of Burgau, and Gottfried of Marstetten. The childless Ulten later transferred his possessions to his relative, Bishop Egno of Brixen, but eventually sold them to Emperor Frederick II of the Hohenstaufen dynasty—sparking the conflicts of the 1250s. Another part of the Ronsberg inheritance went to Berthold of Neiffen, son-in-law of the Count of Marstetten, and included Auenstein Castle as part of the family’s hereditary lands.
By the time Berthold donated Auenstein to the Bishop of Brixen in 1259, the fortress had already lost its importance. It was likely abandoned and falling into ruin, and after this mention it disappears completely from the written record.
Today, only a few fragments of masnory remain to remind visitors of Auenstein Castle. They consist mainly of three parallel walls of different heights, with traces of cross walls attached at right angles. These are probably the remains of a square building that may once have stood within an enclosing wall, though its existence and layout can no longer be traced. The castle was never very large and appears to have been built within a short period—something also suggested by the rough character of its stonework.
