A Peek Inside Berlin's Queer Club Scene Before Hitler Destroyed It -- Queer Identities and Politics in Germany: A History, 1880-1945 by Clayton J. Whisnant
As early as the turn of the century, Berlin’s gay scene was attracting such notoriety that it frequently was mentioned in tourist literature, lifting up the city’s gay scene as proof of the evils of urban life and the dangers of modernity; in them, Berlin became the country’s Sodom and Gomorrah put together, a sure sign of the land’s degeneracy.

On the stages of Berlin, the Tiller Girls showed off their legs, dancing a Rockettes-style performance that amazed and titillated spectators. In crowded cabarets, audiences admired “tableaux” of women posing naked or watched actors telling risqué jokes and singing lewd songs

Clubs full of men wearing powder and rouge as well as shorthaired women dressed in tuxedoes offered images of a world seemingly turned upside down. For the general public, this world was bewildering—and quite possibly terrifying.

For Germany’s gay men and lesbians, though, Berlin represented promise. Its gay scenes offered exciting places to hunt for love and happiness. Christopher Isherwood, whose short stories based on his stay in Berlin eventually became the basis for the 1972 film Cabaret, with Liza Minnelli, put it simply enough: “Berlin meant boys.”
The rest of the excerpt is also good.

It must be noted that some early Nazis were gay, like Adolf Hitler's close friend and SA-militia head, Ernst Röhm. But after the Nazis took over, they arrested some 100,000 people for open homosexuality, and put into concentration camps some 50,000 of them. Their pink-triangle badge for gay-male inmates later became a gay symbol. ER himself was soon deposed in a purge and executed, the Night of the Long Knives.