The book called A Complete Concordance to the American Standard Version of the Holy Bible: A help specially designed to promote the study and to aid in the clear understanding of the Word of God, by M. C. Hazard, Ph.D. (copyright 1922 by Thomas Nelson & Sons and published by them) says the following under the heading of "SHEOL". "The supposed placed of the dead, to which all go, and conceived of as in the depths of the earth. It is a vast, gloomy region, entered in through gates. To what extent its inhabitants were believed to be conscious is uncertain. It is also called the pit (Ps. 28:1; 30:3, and Abaddon (destruction) in Jb. 26:6; 28:22; Pr. 15:11, etc.)". Notice the phrases which I placed in boldface.
The same concordance under the heading of "HADES" says the following. "The abode of the dead, supposed to be in the center of the earth."
I own a copy of that concordance.