Wear black, speak German, and be achingly cool but without trying. Berghain, the Berlin nightclub which is part techno powerhouse part gay fetish club, is infamous for its strict door policy and ban on photography.

So, despite its hallowed reputation, few people know what lies past its blocky, concrete exterior. And accounts by “chosen ones” who are let in are equally vague (‘it was very dark inside. There was lots of sex, lots of leather’).

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Now, artist Felix Scheinberger’s illustrations of the nightclub and other spots in Berlin's underground fetish club scene offer a fascinating insight into a world that remains mysterious in order to protect its LGBT clientele.

Scheinberger, who previously turned his pen to Hamburg’s ‘90s punk scene, started his project in 2011 when a Berlin newspaper asked him to depict the club for an article.

"I go out in normal clothes...black trousers, black shirt," Scheinberger told ID. "Usually I go with friends, we drink something and go dancing. The only difference is that I always have my sketchbook with me. Such kind of drawings can not be made 'from the outside'."

And despite entering the clubs countless times, Scheinberger admitted that he fears rejection "every time I stand in line."

Since opening in 2007, Berghain's door policy has been a point of contention, with some slamming it as elitist while others defending it as a necessary safeguard for its customers.

Earlier this year, US TV host Conan O’Brien was criticised by DJ and Berghain regular The Black Madonna for filming outside of the club.

"He's taking millions of people into a space that is private for a good reason,” the Black Madonna, whose real name is Marea Stamper, wrote on Instagram. “I’m not humorless about any subject. But turning a space like this into a comedy spectacle for a largely straight American audience with no context other than the club being private and gay is a problem," she added, Fact Mag reported.