I took the hop on hop off tour in Potsdam.
Suddenly I heard the sound of azaan on the audio guide and then the words that the building you see in front of you may look like a mosque but no azaan has ever been recited here. It isn’t a mosque!
Though the bus didnt stop there it excited my curiosity and i got down at the next stop. Another Co passenger showed interest so we both walked back.
it is actually The Steam Engine Building.
“Frederick William IV, the “Romantic on the throne,” had Ludwig Persius construct Prussia’s most beautiful power plant from 1841–43, resulting in the only pump station created in a Moorish style. The building, which at that time could still be seen from Sanssouci Palace, set a picturesque and architectural accent in Potsdam’s cultural landscape.”
it was locked so the interior photos are from the net.
“In October 1842 the steam engine in the “Mosque” (capable of 81.4 hp) went into operation for the first time, sending a jet of water in the Great Fountain in front of Sanssouci Palace soaring to an impressive height of 38 meters. August Borsig, who was still a young entrepreneur, had built for Prussia the most powerful machine of its time, allowing King Frederick William IV to compete with the technical supremacy of England.
Although water supply to the fountains in Sanssouci Park is now carried out by modern electric pumps, visitors to the “Mosque” can marvel at technical ingenuity of the past that is still in use – a fascination shared by young and old alike.”
https://www.spsg.de/en/palaces-gardens/object/steam-engine-building-mosque/