Anyone who has holidayed in a Muslim country knows the sound of the muezzin reciting the adhan, calling the faithful to prayer five times per day. But with only 20,000 believers in the predominantly Christian city of Graz, another solution needed to be found.
With the start of the Muslim holy month of Ramadan on Saturday, Friday evening will see for the first time a call to prayer from the minaret of the new mosque in Graz - using light instead of sound, reported Austria's Kleine Zeitung newspaper.
The mosque has a new construction on its minaret, consisting of backlit sheets of bronze, on which will appear the calligraphy of the call to prayer. Combined with this will be smartphone apps which will alert the faithful, meaning that the call to prayer is sent at radio frequencies rather than audio frequencies, as well as with light.