One of the three is Sabrina Vorberg, a 26-year-old Christian, who leads tours around the huge building, explaining to visitors how and why the mosque functions and is used.
“We were all surprised how strong the interest has been,” she said. “We had not expected such a rush of people.”
As a student of Islamic studies, Vorberg knows what she is talking about, but as Christian, she does not pray in the mosque – and therefore does not wear a headscarf when inside it.
“At first I thought I should wear one out of respect,” she said. “But because I don't pray here, it is not necessary.”
She leads tours through the prayer room, explaining the glittery blue dome with the gold writing on it, the prayer niches and even why Muslims take their shoes off before they enter the mosque.
“When they pray, the worshippers touch their heads on the floor, so the room has to be very clean, that is really important,” she said.
Some visitors have come from as far as Japan and Brazil, to examine how the construction of such a large mosque in Germany was undertaken – from a town planning as well as a social perspective.