Windowless

There’s plenty of reasons why a room may not have windows.

The simplest reason is that it’s inside a building. That doesn’t automatically preclude windows, but it certainly lowers the chances. There’s the related issue of being below ground level, too.

Or maybe it’s about controlling some aspect of the room. If it has to be kept cold, or dark, or quiet, any number of variables that a window would mess up, for perfectly legitimate, normal reasons.

But when you wake up in one tied up and gagged, even if it wasn’t designed for that, it’s still clearly been adapted.