1. Setting in a castle. The action takes place in and around an old castle, sometimes seemingly abandoned, sometimes occupied. The castle often contains secret passages, trap doors, secret rooms,trick panels with hidden levers, dark or hidden staircases, and possibly ruined sections.
The castle may be near or connected to caves, which lend their own haunting flavor with their darkness, uneven floors, branchings, claustrophobia, and mystery. And in horror-gothic, caves are often seem home to terrifying creatures such as monsters, or deviant forms of humans: vampires, zombies, wolfmen.
Translated into modern filmmaking, the setting might be in an old house or mansion--or even a new house--where unusual camera angles, sustained close ups during movement, and darkness or shadows create the same sense of claustrophobia and entrapment. The house might be already dark, perhaps because it was abandoned, or it might begin light and airy, but either night comes and people turn off the lights to go to bed, or at some dramatic point the lights will fail (often because of a raging storm).
The goal of the dark and mysterious setting is to create a sense of unease and foreboding, contributing toward the atmosphere element.
2. An atmosphere of mystery and suspense.The work is pervaded by a threatening feeling, a fear enhanced by the unknown. This atmosphere is sometimes advanced when characters see only a glimpse of something--was that a person rushing out the window or only the wind blowing a curtain? Is that creaking sound coming from someone's step on the squeaky floor, or only the normal sounds of the night? Often the plot itself is built around a mystery, such as unknown parentage, a disappearance, or some other inexplicable event. People disappear or show up dead inexplicably. Elements 3, 4, and 5 below contribute to this atmosphere.
In modern novels and filmmaking, the inexplicable events are often murders. The bodies are sometimes mutilated in ways that defy explanation--"What kind of monster could do this?" or "Here's the body, but there's no blood." When the corpses start to mount, suspense is raised as to who will get killed next. (In filmmaking, the atmosphere can be created largely by the music. Anyone who has watched a horror movie with the sound off or very low knows this.)
3. An ancient prophecy is connected with the castle or its inhabitants (either former or present). The prophecy is usually obscure, partial, or confusing. "What could it mean?" In more watered down modern examples, this may amount to merely a legend: "It's said that the ghost of old man Krebs still wanders these halls."
4. Omens, portents, visions. A character may have a disturbing dream vision, or some phenomenon may be seen as a portent of coming events. For example, if the statue of the lord of the manor falls over, it may portend his death. In modern fiction, a character might see something (a shadowy figure stabbing another shadowy figure) and think that it was a dream. This might be thought of as an "imitation vision." Sometimes an omen will be used for foreshadowing, while other writers will tweak the reader