Sankt Perskyrkan, Sigtuna, Medieval church ruins in Sigtuna, Sweden.

Sankt Pers kyrka is a ruined medieval church on a hill in western Sigtuna, next to the vicarage. Its square central tower still stands, with five high, through-going beam holes per side, and the two-aisled nave has vaults and columns in the middle. Outside, the intended foundation of an unfinished westwork can be traced.

Construction began around 1120 with a central tower, and the church became the archdiocese cathedral before the seat moved to Uppsala in 1190. This shift marked a turning point in Sigtuna's importance as a religious center.

The church ruins represent one of seven medieval religious buildings that once lined a street behind the oldest settlement area of Sigtuna.

The hilltop location offers good sightlines to the old walls and their structure from different angles. Visitors should wear sturdy shoes as the ground is uneven and the ruins invite close exploration.

Each side of the square tower has five high, through-going holes in which traces of wood were found. Gunnar Redelius argued in 1970 that beams of about 20 cm across were too heavy for scaffolding alone and may have carried bells, a tower roof and an outer gallery for lookout and defence.