The Cask of Amontillado has Gothic setting by the use of old run down structures. "within the wall thus exposed by the displacing of the bones, we perceived a still interior crypt or recess... for no especial use..." (pg.5). The grave that Montresor makes for Fortunato is an example of Gothic literature because it is a secret room.
The drops of moisture tickle among the bones. Come, we will go back ere it is too late. Your cough--
The protagonist is gothic by the emotion he expresses. "we will go back in; your health is precious; your rich, respected, admired, beloved; you are happy as I once was" (pg.3) Montresor is jealous of Fortunato which makes him a gothic protagonist.
There is some sort of Decay
Ha! Ha! Ha! Ha! He, He, He-- a very good joke, indeed --an excellent jest.
The Cask of Amontillado includes a heightened sense of drama when Montresor murders Fortunato and feels satisfaction from it. "The noise lasted several minutes during which that I might hearken to it with more satisfaction." (pg.6) Montresor is happy to hear Fortunato cry, while he is killing him.
The Cask of Amontillado exemplifies foreboding with the use of ominous implications precede dark events. "we passed through long walls of piled skeletons, with casks and puncheons intermingling, into the inmost recesses of the catacombs." (pg. 4) Montresor took Fortunato through a room of skeletons and Fortunato suspected nothing.
It is nothing, let us go on! But first, another draught of the Medoc.
There is an overall impression of decay in The Cask of Amontillado. "It was succeeded by a sad voice, which I had difficulty in recognizing as that of the noble Fortunato." (pg. 6) Montresor realizes there is no going back and Fortunato grows weak.
The Cask of Amontillado contains a supernatural element that ultimately has a rational explanation. "I had scarcely laid the first tier of the masonry when I discovered that the intoxication of Fortunato had in a great measure worn off." (pg. 6) Montresor had gotten Fortunato pretty drunk he couldn't have sobered up that fast.