The word "Sheol" means a "hollow subterranean place," therefore "Hades" must mean the same.
It has "gates," for Jesus said that the "Gates of Hell" (Hades), should not prevail against the Church. Mt 16:18. And Jesus after His return from "The Underworld," said-- "I am He that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the `KEYS' (of the Gates) of hell (Hades) and of death (the Grave)." Re 1:18.
To get these "Keys" Jesus had to descend into the "lower parts of the earth." Eph 4:9. The Apostolic Creed says that Jesus descended into "Hell" (Hades).
Therefore Hades, or "The Underworld," must be in the "heart of the earth," and is so pictured on the Chart. Jesus said to the penitent Thief "TODAY shalt thou be with me in `Paradise.'" Lu 23:43. And as Jesus "that day" descended into "The Underworld" or "Hades," "Paradise" must have been in Christ's day in "Hades." But as it had been prophesied of Jesus that His "SOUL" (for His body was in Joseph's Tomb on the surface of the earth) should not remain in "Hell" (Hades), (Ps 16:10; Ac 2:27), therefore, before His body could see corruption, Jesus came back from "Hades." But He did not come back alone. He seized the "Keys of Hades," unlocked the Gates of the Paradise Section in which He was confined, and emptied it of its captives, and when He ascended on high He took them to the Paradise section of the "Third Heaven", where they now are, and since then the Paradise Section of "The Underworld" has been empty. Eph 4:8-10.
In the account of the experience of the "Rich Man" and "Lazarus" in the other world (Lu 16:19-31), Jesus gives us a description of "The Underworld" as it was in His day. According to the narrative, for it is not a parable, for parables do not give proper names as Abraham and Lazarus, both the "Rich Man" and Lazarus had died and their bodies had been buried, and what happened to them in the "Underworld," was descriptive of what happened to them in their "disembodied state."
In that state they were conscious, could see, hear, speak, and recognized each other. The difference was that Lazarus was in the "Paradise" section of the "Underworld", typified by Abraham's "bosom," while the "Rich Man" was in the "Hell" section , not the final Hell, which is "Gehenna" (Lake of Fire), but in the section of the "Underworld" where the "souls" of the "Wicked" dead go, and remain until the resurrection of the "Wicked" dead. Between the "Paradise" section, and the "Hell" section of the "Underworld" there is an "Impassable Gulf", (Lu 16:26), which reveals the fact that there is no possibility of the "Wicked" dead ever getting out of "Hell" into "Paradise."