For the first purpose-built brothel in Antwerp's new "tolerance zone" Franky De Coninck, Villa Tinto's owner, hired Quinze&Milan --a famous Belgian designer who has created furniture for Brad Pitt's LA mansion and for Rem Koolhaas's Seattle Library-- after reading in a newspaper that Arne Quinze had always dreamt of designing an upmarket bordello: "It's the biggest business in the world, it's always seen as not so beautiful. But if you show the beautiful part of it, I think you can build an erotic style."

Mr. Quinze set up a consultation committee of prostitutes. They asked him to install red and black neon lights that would illuminate the women inside the display windows but also hide blemishes. Tilted mirrors on the floors of their windows ensure that they can vet clients as they approach and decide whether to open their windows for business.

Like scientific laboratories and military facilities, biometric technology has been incorporated into the brothel's design. To prevent an approved prostitute from handing over her room to an illegal one, she has to press her finger on her room's sensor every hour, or the electricity and heating automatically shut down.

In case of trouble from clients, prostitutes can press a panic button next to their bed, which calls police (there's even a police station "on site") and triggers a red flashing light in the brothel's control room.