Catholic Church of St. Martin on Kirchbühl with Ossuary, Romanesque Catholic church in Kirchbühl, Switzerland.

St. Martin auf Kirchbühl is a Romanesque-Gothic church on a rise above Lake Sempach in the hamlet of Kirchbühl. Its most conspicuous feature is the so-called Käsibissen tower: sandstone up to the height of the nave, rubble stone above. The nave walls are covered with frescoes of around 1300, and a late-Gothic choir with tracery windows was added in the late 16th century.

St. Martin is first documented in 1234, though the building is older. In 1275 it was named the richest church of the deanery; in 1288 it belonged to Murbach Abbey, which ceded it to St. Leodegar in Lucerne in 1420. It served as Sempach's parish church from the 13th century until 1832, when the cemetery was moved into town and the church abandoned.

The interior features painted walls from the 1300s showing Christ, Mary, and saints in bright colors that fill the entire space. These images tell biblical stories and reveal how people of that era understood and connected with religious teachings.

The church stands on the south slope of the Eichberg above Lake Sempach, about a 30-minute climb from the centre of Sempach, outside the old town walls. The cemetery was moved into the town in 1832, so the church was abandoned; the wrought-iron grave crosses on the overgrown churchyard were restored and put back on the old graves in 1964. The ossuary at the churchyard entrance, a square late-Gothic building consecrated in 1575, stands beside the path.

The churchyard's wrought-iron grave crosses, restored in 1964 by the Sempach locksmith Ineichen, were put back on the old graves after the cemetery had fallen into neglect. The church itself was abandoned in 1832, when the burial ground was moved into the town of Sempach.