Transparency is one of the biggest trends in modern office design: open floor plans, fewer offices, glass walls and doors. And at a time when #MeToo has called attention to the sordid things that can happen behind closed doors, there may be some comfort in having everything, and everyone, within view.

But a taste for hidden places still runs deep.

They have appeared throughout history, from secret passageways in medieval castles to Prohibition-era speakeasies. Secret rooms are now popping up in workplaces and other commercial settings, providing the thrill of seeing a room materialize unexpectedly, not to mention the appeal of hanging out in a space reserved for V.I.P.s.