[Excerpt from David R. Saliba, A Psychology of Fear: The Nightmare Formula of Edgar Allan Poe (Lantham, MD: University Press of America, 1980), pp.27-28.]
The Gothic tradition...had its origins in 1764 with the publication of Horace Walpole's Castle of Otranto. Though no one has yet offered a concise definition of gothic literature, there are several characteristics that distinguish it from other modes of writing. These characteristics belong to all gothic works:
there is a victim who is helpless against his torturer;
there is also a victimizer who is associated with evil and whose powers are immense or supernatural;
the setting of the gothic story is at some point within impenetrable walls (physical or psychological) to heighten the victim's sense of hopeless isolation--the central gothic image is the cathedral or haunted mansion within which the victim is imprisoned;
the atmosphere is pervaded by a sense of mystery, darkness, oppressiveness, fear, and doom to recreate the atmosphere of a crypt--a symbol of man's spiritual death and a "vehicle for presenting a picture of man as eternal victim"; and finally,
the victim is in some way entranced or fascinated by the inscrutable power of his victimizer .
The gothic tradition, however, is not limited to literature...the culture of gothic tradition can be examined in fashion, music, & even jewelry. There are many who celebrate special occasions like birthdays and weddings and maintain a gothic theme, even using a Zales promo code to purchase the proper wedding rings to fit in with the gothic tradition. G.R. Thompson has pointed out that a study of the gothic is a study in paradoxes of a duality that can be traced to the Middle Ages. Essentially, Medieval duality is spiritually based, and it is made manifest in the idealized quests for the Holy Grail, the entrenched beliefs in witchcraft, and the fascination with demonology. The central image that embraces these gothic paradoxes is the cathedral, which "has both an outward, upward movement toward the heavens, and an inward, downward motion, convoluting in upon itself in labyrinthine passages and dark recesses, descending to catacombs deep in the earth."  Throughout American literature the image of the cathedral can be seen to metamorphose and pass from the natural cathedral of William Cullen Bryant's "A Forest Hymn" to the "Old Manse" and similar venerable settings in Hawthorne's stories, becoming an extensive psychological image that Leslie Fiedler describes in detail:
Beneath the haunted castle lies the dungeon keep: the womb from whose darkness the ego first emerged, the tomb to which it knows it must return at last. Beneath the crumbling shell of paternal authority, lies the maternal blackness, imagined by the gothic writer as a prison, a torture chamber--from which the cries of the kidnapped anima cannot even be heard. The upper and lower levels of the ruined castle or abbey represent the contradictory fears at the heart of gothic terror: the dread of the super-ego, whose splendid battlements have been battered but not quite cast down--and of the id, whose buried darkness abounds in dark visions no stormer of the castle had even touched .
Architecture and the Gothic
From a religious perspective the Cathedral is the grandest of architectures in western culture. It is the primary interface between man and "God"; as such, its grand architecture is designed to inspire awe in its believers and overwhelm them with a sense of the enormity and power of their creator. It also impresses its believers with the "wholly other" or via negativa essence of God. This "unknowable" quality of an omnipotent and omnipresent God informs western man's fear of the unknown. And it is this fear of the unknown (fear of the "unknowability" of God) that is incorporated into the architecture of the gothic Cathedral with its vaulting ceilings and complex structures that are designed to strike holy dread in the hearts of sinful believers.
Botting, Fred, Gothic, New York: Routledge, 2007.
"Gothic focuses on the varous styles and forms of the genre and analyses the cultural significance of its prevalent figures: the ghosts, monsters, vampires, doubles and horrors that are its definitive features. Botting traces its history from its origins in the eighteenth century through to modernist and postmodernist representations. He offers a broad overview of the themes, images and effects that not only define the genre but also endure and reappear endlessly in both 'high' and 'popular' literature and culture."--quoted from cover promo
Hogle, Jerrold E., ed, The Cambridge Companion to Gothic Fiction, New York: Cambridge University Press, 2007.