Altenberger Dom, Former Cistercian abbey church in Altenberg, Odenthal, Germany

The Altenberger Dom is the former Cistercian abbey church in Odenthal-Altenberg, built from 1255 in Gothic style from Drachenfels trachyte. It is a three-aisled basilica with a transept and an ambulatory with seven radial chapels, but no west towers. The choir was consecrated in 1287, and the large west window was installed around 1400.

Construction began in 1259 when Archbishop Konrad von Hochstaden laid the foundation, taking roughly 140 years to complete under Cistercian direction. During this extended building period, it became the most important religious structure in the region.

The building has served as a shared place of worship for Catholic and Protestant communities since 1857, when King Friedrich Wilhelm IV. ordered its joint use. Visitors today see both denominations using the same sanctuary for their services and gatherings.

The building is open throughout the year, with concerts and sacred music performances, particularly featuring the Klais organ with 6300 pipes, occurring mainly from May through October. Visitors can generally enter for worship services and cultural events with no admission fee.

The church was the burial place of the counts and dukes of Berg and of Jülich-Berg until 1511. Bishop Wikbold Dobilstein of Kulm, who consecrated the church in 1379, is buried in the high choir. The late-Gothic eagle lectern of 1449 was moved to the Maxkirche in Düsseldorf after the abbey was dissolved in 1803.