Altenberg Cathedral

Altenberg Cathedral does not stand in a city but in the middle of the wooded Dhünn valley, a good 20 kilometres north-east of Cologne. That makes the tall Gothic church rising between meadows and monastery buildings all the more surprising. Altenberg was never a bishop's seat; the former Cistercian church is called a "Dom" because of its cathedral-like size. Its most famous feature is the west window: 144 square metres of stained glass, the largest Gothic window north of the Alps.

History: abbey, chemical works, shared church

Cistercian monks came to Altenberg in 1133. By the end of the 12th century there were 107 choir monks and 138 lay brothers, and the first Romanesque church had become too small. On 3 March 1259 Count Adolf IV of Berg laid the foundation stone of the new church, barely later than work began on the cathedrals of Cologne and Utrecht. The choir was consecrated in 1287 and the whole church in 1379. Until 1511 the counts and dukes of Berg were buried here.

After the abbey was dissolved in 1803, decline followed. A wine merchant bought the site and tenants set up a chemical works producing Prussian blue. On the night of 6–7 November 1815 an explosion started a fire that destroyed the monastery buildings and the church roof. By 1835 parts of the transept, crossing and choir had collapsed, and the ruin was used for a time as a quarry. Rescue began in 1834, with King Frederick William III paying most of the cost. His son attached a condition: the church was to belong to both denominations. Since the first Protestant service on 13 August 1857, Altenberg has been a shared Catholic and Protestant church. It is owned by the state of North Rhine-Westphalia.

What to see

• West window: Designed around 1390 and installed shortly before 1400, it shows the Heavenly Jerusalem. At its centre kneel the donors, Duke William II of Berg and Anna of the Palatinate. It glows most strongly in the afternoon, when the sun comes from the west.
• Grisaille windows: The restrained grey-and-white glass elsewhere is typically Cistercian; the order long frowned on display.
• Altenberg Madonna: The radiant Madonna of 1530 hangs freely above the altar and is carved on both sides.
• Ducal choir and tombs: Among those buried here are Adolf IV of Berg and Duke William II. A niche in the axial chapel holds the heart of Archbishop Engelbert of Cologne.
• Organ: The Klais instrument of 1980 has around 6,300 pipes, the largest 12 metres long.

Good to know

Shared use is still strictly scheduled: the Protestant congregation has the church daily from 8 to 10 am and from 1:30 to 3:30 pm, the rest of the time belongs to the Catholics. In 2012 two head relics missing since the 18th century turned up in a box in the sacristy of the parish church in Odenthal. Since 2014 they have been back in Altenberg in a double reliquary by Heinz Mack. From the 1920s, Haus Altenberg next to the church was the centre of Catholic youth work in Germany.

Visiting and timing

The church is open during the day; sightseeing is not possible during services. From May to October there is sacred music on Sundays at 11:45 (Catholic) and 14:30 (Protestant), plus a concert programme run by both parishes. Allow 30 to 60 minutes for the church itself, or half a day with a walk in the Dhünn valley. Altenberg belongs to the municipality of Odenthal; the drive from Cologne is a little over 20 kilometres.

Tripto tip

After your visit, stand on the lawn in front of the west front. Only from there do you see how the huge window fills almost the whole facade, and how plain the building otherwise is: no tower, just a small roof turret, exactly as the Cistercian rule required.