The cage was located in a specially reinforced ship cabin, where the narrow, damp, and sweltering chamber was divided by iron bars into a dozen or so cages of varying sizes, imprisoning the "sacrifices" within.
Entering such a place could never bring about any good experience—even Lucresia would slightly furrow her brow upon stepping into this prison.
By the time Duncan arrived here, the originally caged victims had already been transferred to an open space at the end of the cabin—the environment there was somewhat better, and it was right next to a vent, which seemed to be a spot where the guards had stayed temporarily.