Cyriaksruine, Romanesque church ruin in Dornburg-Camburg, Germany.

The Cyriaksruine is a church ruin located in the forest near Camburg with visible stone remains and Romanesque architectural features still intact. The preserved walls and arches are scattered across the site, giving a sense of the building's former scale and structure.

A note in Thietmar of Merseburg's chronicle, written between 996 and 1002, records Countess Christina giving part of her estate at Stuwi to Saint Maurice in Magdeburg. In 1121 a papal confirmation placed the church of Stubi under the Augustinian monastery of Neuwerk near Halle. It served as a parish church until 1539, when the Reformation led to its dissolution and use as a quarry.

The name comes from Saint Cyriacus, to whom the church was dedicated. Every two years the Cyriakusfest, a large archery tournament with a medieval spectacle, takes place in and around the ruin. Since the altar was renewed and consecrated, summer services are held on the site.

The ruin is located in the forest about 1.5 kilometers from Camburg and is accessible year-round. A parking area near the site makes visiting convenient, even though the approach involves a walk through woodland.

The stone from this church ruin was salvaged and built into houses and walls of nearby villages after the building was abandoned. Many regional structures today contain materials originally taken from this site.