Burgruine Gallenstein, Medieval castle ruins in Sankt Gallen, Austria.

Burgruine Gallenstein is a medieval castle ruin in Sankt Gallen, Austria, situated at 631 meters above sea level in the Styrian landscape. The structure preserves three Gothic towers, including a large residential tower with thick walls and window openings from different periods.

Rudolf of Habsburg granted Abbot Heinrich II of Admont permission to build fortifications in 1278, which is taken as the start of Gallenstein. Around 1290 the Gothic chapel of St. Peter was added. The castle remained the abbey's refuge and administrative seat until the end of the 19th century, and in 1491 the imprisoned abbot Antonius Gratiadei died here.

The courtyard hosts an annual summer cultural festival, and the ruins also stage concerts and exhibitions, including the Festival St. Gallen. The von Gallenstein noble family once resided at the castle.

Two routes lead up to the ruin: the steep "Alter Burgweg" through a forework that was hard to overcome, and the newer Burgweg, usable by vehicles, which passes through a tunnel that did not exist in the Middle Ages. The old approach shows why the castle was never taken in combat.

In 1832, the copper roof was removed to avoid taxes, which caused the structure to deteriorate rapidly without proper protection. This deliberate stripping of a key element led to restoration work by the local heritage society decades later.