Though it’s half hidden behind a tire store along a busy highway, the two-story, red neon sign makes it hard to miss Berlin’s biggest brothel. Open since last September, Club Artemis is strategically placed just a few subway stops from the venue for the World Cup final, the 74,000 seat Olympic Stadium. It is also at the center of the biggest controversy of the World Cup: Are women being trafficked into Germany to allow soccer fans to score off the field?

The German sex industry, legalized in 2002, is expecting a 30 percent boom in business during the tournament. Brothels have been opening in host cities like spring flowers, temporary trailers (generously dubbed “performance boxes”) have been built near some cup stadiums, and organizers plan to distribute 750,000 free condoms during the games. “With six games in Berlin, we’re expecting some very high-intensity days,” says Artemis press spokesperson Vanessa Rahn. “We’re looking forward to a big rise in business.” That has led to howls of protest from everyone from New Jersey Republicans to European women’s rights groups. They claim that East European women will be smuggled into the country to meet the soccer fraternity’s sexual needs.

Inside Artemis, there is little sign of the public controversy brewing outside. The bordello includes the usual trademarks: dark red carpets, overstuffed leather sofas, stripper poles, way too much gold paint, round beds under huge mirrors, and mock Greco-Roman murals. Like similar clubs in Hamburg and Cologne, it’s a testament to erotic excess. From 11 a.m. to 5 a.m., dozens of prostitutes can be found wandering the four-story, 4,000 sq. meter club in the buff—except, of course, on “Lingerie Wednesdays.” (During the tournament, management is considering keeping...