Burgruine Dornach, Medieval castle ruin in Lasberg, Austria

Burgruine Dornach is a castle ruin in Lasberg situated at about 530 meters elevation overlooking the rolling countryside of the Mühlviertel region. The structure includes preserved stone walls, a gate tower, and outer fortifications that still convey its former defensive purpose.

The ruin was first recorded in 1416, though it faced severe damage from Hussite raids in 1427. After this attack, ownership changed and the site gradually fell into disrepair.

The name Dornach comes from the hilltop site itself, not from a village. At the Lasberg cultural days, knight games were held in the restored ruin, recalling fighting near the Feistritz-Feldaist confluence between Dornach and Weinberg; finds of old weapons and armour pieces suggest such clashes. The Meierhof linked to the castle, the Dornachhof or Hartmayrhof in Siegelsdorf, was where Johann Blöchl, called the father of the Mühlviertel, was born in 1895.

The ruin stands about 1.5 km west of Lasberg in the Siegelsdorf hamlet, on a slope above the Feistritztal near where the Feistritz meets the Feldaist. It is reached on foot; the rock edge by the walls drops steeply, so watch your step. Part of the former castle has been renovated since 1963 and is lived in, so the inhabited section is not open to visitors.

Stone removal from the ruin was not licensed from 1505; it continued unchecked until 1821, when Count Josef Thürheim of Weinberg forbade the demolition of the walls. By then, local people had long used the masonry as building material for their houses.