Burgruine Kirnstein: A Medieval Castle Ruin in Flintsbach, Germany

Visitor Information

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Country: Germany

Civilization: Unclassified

Remains: Military

History

Burgruine Kirnstein is located in the municipality of Flintsbach in modern-day Germany. It was built during the 12th century by the Neuburg-Falkenstein family, a powerful noble line, to serve as a ministerial seat overseeing the Inn Valley. This site’s early significance is attested by a figure named Leoprant de Churne, recorded around 1130 as a witness to legal matters involving Count Wolfger of Falkenstein, linking the castle to the region’s feudal nobility.

Throughout its history, Kirnstein controlled a key old road navigating the narrow Inn Valley, underscoring its strategic importance. After the decline of the Falkenstein family, the castle changed hands multiple times. In 1247 it came under the control of the Wittelsbach dynasty, renowned rulers in Bavarian history. By 1361, ownership shifted to the Preysing family from Wolnzach, then to Seitz von Laimering in 1400, and shortly afterward, in 1405, to the Dukes of Bavaria-Ingolstadt. These frequent transfers reflect the castle’s ongoing value within regional power dynamics.

The castle suffered its first destruction around 1430 during the Bavarian Landesteilung, a civil war among Bavarian dukes. In this conflict, opposing factions led by Dukes Ernst of Munich and Heinrich of Landshut burned the fortress as part of their struggle against Duke Ludwig the Bearded. Afterward, the Dukes of Bavaria-Landshut took control, rebuilt the castle, and granted it as a fief to Erasmus Waltenhofer, marking a phase of reconstruction and renewed feudal administration.

A second and final destruction occurred during the Bavarian War of 1504. By the late 16th century, the castle was already noted in historical records as a ruin. In 1568, the cartographer Philipp Apian described it as “a castle situated on a mountain,” while by 1585 Wiguleus Hund referred to it as a “broken castle,” indicating its deteriorated state in the decades following the war. Much later, in 2002, the west wall of the structure collapsed as a result of storm damage. Today, Burgruine Kirnstein is recognized as a protected historic monument and archaeological site, with documented underground remains reflecting both medieval and early modern use connected to the castle and a nearby pass barrier.

Remains

The ruins of Burgruine Kirnstein sit on a narrow spur of the Wildbarren mountain at about 520 meters elevation, rising above the valley floor on the mountain’s eastern slope. The castle’s main enclosure formed a roughly square shape measuring approximately 18 by 16 meters. Its walls, originally built from rubble stone combined with more finely cut corner stones known as ashlar blocks, were about 1.2 meters thick and survive today up to a height of eight meters in places. Most of this masonry reflects the rebuilding activities following the destruction around 1430.

On the north side of the enclosure, the castle’s entrance was located. Today, visitors can see a partially preserved section of the masonry gate arch, although only a small fragment protrudes above ground level. This gate would have served as the primary controlled access point to the inner castle.

At the southeast corner of the enclosure, the foundation suggests a projecting section roughly five meters long and two meters high. This feature likely belonged to a residential building known as a palas, positioned on the southern side of the complex. The remaining area within the walls was probably used as a courtyard space. The castle’s western edge was naturally defended by a steep slope from which it was further protected by a neck ditch—a deep, narrow trench designed to prevent attackers from approaching easily.

Below the eastern side of the castle hill lies a terrace separated from the main fortress by a ditch and an outer rampart, earthworks that likely formed an outer courtyard or bailey. This area would have supported auxiliary functions such as storage or housing for servants and animals. Across the site, medieval and early modern underground remains, including elements related to a pass barrier controlling access through the valley, have been identified through archaeological investigation. These features contribute to understanding the castle’s military and administrative roles in the rugged Inn Valley landscape.