Schlosskirche Haigerloch, Parish church on rocky outcrop, Haigerloch, Germany

Schlosskirche Haigerloch, also called St. Trinitatis, is a parish church built in 1584–1609 in post-Gothic style, reusing Gothic forms no longer current at the time. Its interior has wall pillars drawn inward, side chapels, a west double gallery with a princely box, and a lower choir with a three-eighth close set off the nave's axis. The tower at the northwest corner stands on higher rock and was topped in 1748 with an octagonal bell storey and an onion dome.

Count Christoph von Hohenzollern and his wife Katharina commissioned the church, built between 1584 and 1609 by Hans Stockher and Martin Schill in post-Gothic forms. After damage in the Thirty Years' War, Prince Joseph Friedrich had it baroquified in 1748, when the tower received its octagonal bell storey and onion dome. Restorations followed in 1905–1907, 1956 and 2013–2015.

The church is still the Catholic parish church of Haigerloch, dedicated to the Holy Trinity. Two carved wooden portrait statues on the north nave pillars show views of Haigerloch and Sigmaringen and commemorate the founder Count Christoph and the renovator Prince Joseph. The high altar, consecrated in 1609, is a rare multi-figure Renaissance retable with over 60 wooden sculptures by Virgil Moll.

The church stands on a rock outcrop above Haigerloch, and the tower occupies the northwest corner of the nave at a higher rock level. The choir is offset from the nave axis because of the ground conditions, so the interior layout is not symmetrical. The Atomic Cellar Museum lies directly beneath the church.

Directly beneath the rock on which the church stands, there is a former cellar that was used as a secret laboratory for nuclear fission experiments near the end of World War II. This underground space is now open to visitors as the Atomic Cellar Museum, telling a story that few would connect with the church above.