The Threefold Gates of Hell that lie within the Subconscious, the Earth and on the outer spheres of Hell itself are each connected to a triad of Demons, the numbers three and nine are deeply powerful in Satanism albeit for different reasons.
The corrupting of the number three which reflects the Holy Trinity of Father, Son and Holy Ghost is carried out on many levels we may witness . . . the three scratches left by Demons upon the attacked or possessed, the penchant for Demonic activity at three in the morning two of the most obvious, hence the triad of Gateways which form the entrance into Hell through three differing spheres of existence.
The number nine is sacred to Satan, it is the Omega of the singular numerical values and in opposition to the Alpha number of one which is connected to the Godhead, Monotheism and autonomy.
The number of the Beast 666 when divided and added up forms the number nine (6+6+6 = 18, 1+8 = 9) . . . numerically the number one is autonomous, a number of tyranny, direction, order, systematic approaches and linear thinking . . . the number nine numerically is more connected with vision, imagination, the Magickal, chaos, conflict and individualism.
The three Gates of Hell represent the blasphemy of the Holy Trinity, the nine Demons attributed to them represent the vanquishing and transcendence of this Holy Trinity through the power of the number nine, the power of Satan.
The First of the three Gates by which Hell may be entered is through that of the subconscious mind, within the darkest reaches of the unexplored regions of the subconscious their lies an Inner Gate and the Spirit governing this Gate is Lilith along with Agaliarept and Abaddon.
The third of these three Gates lies in realms beyond this world in the sphere I call the Shadowrealm which lies between the domain of the physical and the dominion of the Demonic, the Spirit governing this Gate is Satan supported by Beelzeboul and Asmodeus.
The second Gate between the first and third is a Gate which requires intensive exploration, it is a Gate that is said to lie within the Earth itself . . . from personal studies I believe this to be within a subterranean dominion or city within the earth the likes of Agharti or Shambhala.
Such dominions are touched on in many works, Shambhala is referred to in ancient texts such as Kalacakra Tantra and the Tibetan texts of Zhangzhung, the novelist Edward Bulwer-Lytton observes through fictional accounts in his book The Coming Race, in more recent times Alec Maclellan in his book The Lost World Of Agharti has documented such subterranean domains and the author Toyne Newton too discussed it in his book The Demonic Connection.
It is also well documented that Adolf Hitler during the second world war was obsessive in his search for such a dominion and the source of the Vril power which was said to gestate from it.
If this physical Gate to Hell and potent power that generates from it does exist then it would appear it does so within a series of underground tunnels and caves, possibly around the area of Tibet, but such a place could be virtually anywhere such as in the famed catacombs of Paris . . . from studying the aforementioned legends and beliefs one wonders if the underground Kingdom may a physical entrance to Hell and that maybe the race who live within this domain are the Demons themselves.
Past conjecture however such a physical Gate would be governed by the Infernal Spirit Lucifuge Rofocale aided by the Demons Belphegor and Mephistopheles.
The locating and utilization of any of these Gates is a method of great Magickal power and the easiest to locate is obviously the first of these three portals into the spheres of Hell . . . in later Texts within The Black Book methods to enter the Gates are disclosed and discussed along with exploratory techniques for negotiating the hidden Gate within the Earth.