In Edgar Allan Poe's "The Masque of the Red Death," Prince Prospero's party is, very significantly, a masquerade. For everything about this party is masked: The guests are only from the prince's social level--"a thousand hale and light-hearted friends--and the location is in, not his residential castle, but his "castellated abbeys," which are either monasteries or convents. Their resemblance to a castle is only in their castle-like towers.
So, not only are the "friends" disguised, but the location of the party is masked by being within an ostensibly humble, non-secular, and somewhat holy location. Even the rooms are masked as there is no "light of any kind emanating from lamp or candle within the suite of chambers." And, the rooms' windows are painted over, the drapes heavy velvet tapestries that "hung all over the ceiling and down the walls, falling upon the carpets. The outside of the abbey, there is a strong and lofty wall that "girdled it." This wall has gates of iron; thus, the revelers are concealed as well as protected by wall and fence in Prospero's effort to keep the Red Death away.