Trier, St. Peter's Cathedral
It is unique in its design and sound: the large swallow's nest organ in Trier Cathedral, built in 1974 by the internationally renowned Bonn organ builder Johannes Klais.

In the course of extensive renovation and restoration work in the cathedral, planning for a new cathedral organ began in 1970. After much deliberation, the decision was made in favour of a ‘swallow's nest organ’ on the site of the previous cathedral organs dating back to 1832. The Johannes Klais workshop in Bonn was chosen from among the organ builders invited to take part in an ideas competition to build the instrument.
The five-storey organ weighs no less than 30 tonnes and is 16 metres high and 8 metres wide. The Baroque tradition of ornamenting and richly decorating organs is reflected in the sculptural and colourful decoration designed by the sculptors Hillebrand and Heiermann together with the painter Viktor Breiling.
The centre organ case with the four manual stops is flanked by the towers of the pedal (C and C sharp side). For reasons of space, the 32 covered wooden pipes of the 32' lower case are located on their own chest in the biforium behind the organ. Their valve control is electric. The blower system is also located in this area.
The front pipes consist of an upright sounding part and a suspended decorative part. Both approach each other except for the open space between them. The front pipes located in front of the shutters of the swell are particularly noteworthy. They belong to the Hauptwerk and, unlike the other pipes, are suspended.
The console is located between the Rückpositiv and Brustwerk and is attached to the main organ body. The organist can reach it via a lift in the north-west round tower of the cathedral. The way to the biforium behind the organ is via the northern side aisle vault. From here, a staircase leads directly to the console. The organist sits, hidden by the pipe bundles of the Rückpositiv, in the centre of the organ, so to speak.
The connection between keys and pipes, the so-called key action, is made via thin wooden drawbars (abstracts), levers and brackets. The stops and couplers are switched electrically. Thanks to the electronic combinations of stops, any combination of stops can be saved and called up quickly and easily during church services or concerts. Unusual playing assistance is provided in the form of a key sostenuto - which allows any key on the Hauptwerk keyboard to be held in place - and wind release valves for the Hauptwerk and Schwellwerk.