Below the Old City walls in Jerusalem there is a ravine that begins as a gentle, grassy separation between hills, then quickly descends south into the rocky earth. Eventually the ravine becomes a steep, craggy depth, scarred on its far side by shallow caves and pits pocked by hollowed-out chambers and narrow crypts.

Everywhere you see scorches and smolder from trash fires. Rivulets of urine trickle down from open sewers at the cliffs above, watering thorn bushes, weeds and unexpected clumps of grass among the outcroppings. You smell the stench of decaying offal, the congealed stink of putrefied garbage and the absorbed reek of incinerated substances seared into the rock face. Crows circle low. Worms and maggots slither throughout.

Listen. Imagine. Some cannot help but hear the tormented screams of babies being burned alive, the macabre incantations of the idolatrous in gruesome celebration, the agonized cries of helpless victims, and so many echoes of death and disconsolation that dwell here so pervasively not even the centuries can silence them.

Welcome to Hell. Some say the real Hell--or at least one of the central prototypes for our modern concept of that horrific place. This is Jerusalem's Gei Ben Hinnom, the Valley of the Sons of Hinnom. The valley was named for an alien nonsemitic family, the Hinnom clan that predated the First Temple period a thousand years before the Christian era, and established the locale as a place of abomination. Gei Ben Hinnom became Ge Hinnom (Valley of Hinnom), and eventually Gehenna in English or Gehennem in Arabic and Hebrew.

Those who walked through the biblical Valley of the Shadow of Death walked here. Hellish images of unending torture and fire as punishment for a life of evil owe much to this hideous acreage, just a short walk from the path of righteousness that leads to the Temple Mount.

Hellish Sacrifice

Perhaps it is fitting that the path to Hell begins delightfully. In recent years, the northern and inoffensive length of the valley has become a zone of chic Israeli gentrification: exquisite town homes, landscaped parks, a concert bowl at the Sultan's Pool and movie theaters. But, as the ravine carves deeper and deeper between the rocky hills, and as it rounds the corners of Mount Zion into East Jerusalem en route to the Arab village of Silwan, Gei Ben Hinnom conjoins with the Valley of Kidron. Here it traverses a stretch that has become a sort of urban no-man's-land in the struggle between Arab and Israeli.

As land that defies political peace, this is the only part of the valley that Arabs cannot improve and that Jews dare not. Therefore, little has changed here for centuries. Still visible are the original, deep angular cuts into the flat scorched stone that held the infamous Tophet, pagan altars created hundreds of years before Christ. Tophet altars are said to be named for the noisy drum that devotees of the mysterious dark god Molech would beat to drown out the ghastly cries of children immolated in sacrifice in front of their own willing parents.

In the black rapture of their faith, mothers and fathers not only witnessed the sacrifice, but glorified the act. Beneath the ancient Tophet altars, one can still see foreboding square entryways barely big enough for a human torso to squeeze through. Within those depths lay a complex of carved-out crypts, as well as chambers for ritual preparation of the sacrificial victims.

Little is known about Molech. Some archaeologists speculate that the Molech idol in Gei Ben Hinnom was equipped with outstretched, cantilevered arms that extended a small platform upon which the innocent baby was tied. Slowly the platform would swivel toward the consuming flames as the baby shrieked in helpless agony. No wonder this most hideous place is the focus of so much biblical wrath: "He defiled Tophet, which is in the Valley of Ben Hinnom, so that no one would make a son or a daughter pass through fire as an offering to Molech" (II Kings 23:10).

"Therefore the days are surely coming, says the Lord, when this place shall no more be called Tophet, or the Valley of the Sons of Hinnom, but the Valley of Slaughter" (Jeremiah 19:16).

The Hinges of Hades

But how did a very authentic site of pagan abomination help define the concept of eternal punishment we call Hell?

Two separate dynamics have been at play for centuries. The first is the concept of eternal punishment in death for evildoers. The second is the site of that punishment. Both have changed radically over time.

Early Jews believed dead people, good and bad, all descended to the same destination, a nondescript underworld called Sheol.

"There is no concrete Jewish vision of the afterlife," says Rabbi Shalom Carmy, Yeshiva University professor of Jewish studies and philosophy and author of a just-released book, "A Jewish Perspective on the Experience of Suffering."

"Sheol is a place of silence, a place where not even the service of God continues."

But if afterlife in Sheol was nothing to fear, it was certainly nothing to look forward to. Ecclesiastes 9:5 declares, "The dead know nothing and they have no reward."

Ancient Israel, however, was a crossroads, populated by descendants of disparate tribes. Conquest by foreign armies brought foreign ideas that slowly crept into the Jewish mind-set. By the 7th century B.C., Isaiah's writings in 26:19 suggest that "dead corpses shall rise awake and sing."

And Isaiah frequently predicts a punishment by fire for the wicked. The Book of Daniel also predicts resurrection for the godly, and "shame and everlasting contempt" for evildoers.

But earnest Judeo-Christian notions of posthumous reward and punishment for earthly goodness or sin probably originated with the widespread influence of the 6th century B.C. reform Persian prophet Zoroaster and his followers. Zoroastrianism taught that the universe was ruled by two antagonistic gods: the Divine, who dwelled above, and the Lord of Lies, who inhabited a vile underworld. Those judged to have lived a good life were ushered upward, to the Divine. Bad people went below.

By the time of the Pharisees and a Christian precursor sect known as the Essenes in the 2nd century B.C., a school of Judaic thinkers embraced the ideal of immortal resurrection for the good and damnation for sinners, explains Alice K. Turner in "The History of Hell."

But the idea was far from universally accepted. Christianity took centuries to restate, redefine, enhance and finally codify the conflicting Judaic views on death and eternal judgment. The process began in the books of the New Testament, especially as the words of Jesus were recalled and interpreted in parables. Heaven is identified as the destination for godly people. For the unrepentant and wicked, images of Sodom's fiery destruction and burning furnaces of divine retribution are everywhere. Matthew 13:41-42 warns that evildoers will be "thrown into a furnace of fire." Revelation speaks of a "lake of fire" awaiting the damned.

But the references were scattered, and sometimes contradictory. Acrimonious debates over whether references to "eternal damnation" were real or symbolic were eventually settled as part of fierce church politics. Damnation was determined to be real.

In the 4th century, Augustine insisted, "Hell, which is also called a lake of fire and brimstone, will be material fire and torment to the bodies of the damned."

But where would all this take place? The first geographic specifics on Hell were probably invented by the Greeks. Hades--the colorful underworld of Greek myth--was originally the same kind of nullity as the ancient Hebrew idea of Sheol. The word Hades came from the Greek term a des, which means only "the unseen" or concealed. Those who inhabited Hades--good and bad alike--were known as "shades," who existed as nonentities. But great poets and philosophers, such as Plato, Homer, Virgil and Ovid, eventually contributed much of the gore and dismal landscape in classics such as "The Odyssey" and "The Aeneid," according to Turner.

The first Christian attempts to describe Hell owed much to the Greeks. When Dante penned "The Divine Comedy" in the early 14th century, he upped the ante. So convincing was his fantastic architecture of Hell that in the 1500s Galileo was moved to calculate the precise location of the opening to Dante's Hell: He pegged it at 405 15/22 miles below the surface of the Earth.

The impact of Dante's "Inferno" changed the very language. The word inferno derives from the Latin word inferus, which means below or underneath. But because of "The Divine Comedy's" popular impact--and only because of it--the word inferno eventually took on the meaning of a burning place. It came to mean Hell itself.

Milton more or less completed the imagery of Hell when he wrote "Paradise Lost" in the 17th century, furnishing it with dungeons, fiery deluges, burning sulfur and of course awful devils and demons.

"These images were already developing from the 6th century right through the 13th," says David Rodier, American University's chairman of the department of philosophy and religion. "But Milton fixed the picture to the English-speaking world."

Where in Hell . . .

So now the world knew what to expect from Hell. It remained only to locate it. The earliest Judaic notions of the geography of damnation began in Heaven, a literal location in the clouds where God and His angels dwelled. But within that white-as-snow world, there was also a dark place of torment and punishment, arguably the first location of Hell. In an apocryphal book written between testaments, Enoch offers the following vision: "And they brought me to the place of darkness, and to a mountain the point of whose summit reached to heaven. And I came to a river in which the fire flows like water."

In the next chapter Enoch quotes an angel explaining, "This place is the end of heaven and earth: This has become a prison for the stars and the host of heaven [which] have transgressed the commandment of the Lord."

By the time the books of the New Testament were penned, there were 21 references translated as "hell," which speak of a detestable place of fire and damnation. This is where the term Gehenna begins to appear.

Gehenna, the Valley of Hinnom, had a lot going for it in the hellishness department. It had already been singled out as an abomination involving the sins of human sacrifice, torture by fire, and eternal dishonor for the dead. Hinnom's ghastly child sacrifice was halted only in the 7th century B.C. when Josiah overran the valley and desecrated its altars with bones. Eventually, part of Gei Ben Hinnom became a dump, with constant day and night burning of trash fires emitting a sulfurous stench. Another portion of the ravine became a cesspool receiving the sewage of Jerusalem. Indeed, Essenes and other holy men, believing Jerusalem too holy for defecation, fastidiously carried their dung out past the city walls, where they channeled it down to the valley.

What's more, Hinnom was a final resting place for those shamed in death. Proper burial was vital under Judaic law, both to combat the necromancy of early Semitic tribes and to show respect for the cessation of God's most precious gift. The dishonored and unclean were not entitled to a proper Jewish burial within the city. Dishonored corpses were disposed of in the reviled Valley of Hinnom. Those without family to make arrangements were interred in the potter's field--a place where potters worked--situated at one end of the valley, the origin of the term "potter's field" for a burial ground for the lowly.

And according to Greek Orthodox tradition, the valley at Ben Hinnom even figures in the ultimate act of evil: Judas dejectedly relinquished to the priests the 30 pieces of silver he received for his betrayal of Jesus, blood money used to purchase a tract of land that later became the Convent of St. Onuphrious, which today straddles a cliff above the deepest stretch of Gehenna.

The abbey's toilets flush into a crude pipe that regularly drizzles onto the valley below. No wonder the Hinnom ravine became off-limits for all but the unpure. No wonder Gehenna was a symbol of damnation. No wonder in Matthew's many references to the defilement and torment of Hell, the word used is actually "Gehenna."

Matthew warns in 5:29: "So if your right eye causes you to sin, take it out and throw it away! It is better to lose a part of your body than to have your whole body thrown into Hell."

The connection between a sinner's body being thrown into Hell, and literally tossed into a hole in the ground in an unconsecrated burial, is more than coincidence.

"By this time in Christian thought, Gehenna is being used as a contrast to paradise," asserts Walter Mickel, professor of Old Testament at Chicago's Lutheran School of Theology. "Gehenna has now become the bad place for an afterlife. What was the metaphor, that is, the afterlife, becomes the reality. And the physical place becomes the metaphor. Matthew clearly combined all these ideas."

So pervasive was the medieval notion of Gehenna as Hell that it influenced not only Christianity, but much of Jewish thought as well.

"From the 3rd to the 6th centuries, Talmudic tractates wrote of Gehenna as a place of torment," says David Kraemer, professor of Talmud and rabbinics at Jewish Theological Seminary in New York. He cites several passages to make his point. One declares, "The wicked at a future time will be under sentence to suffer in Gehenna."

Another reads, "The wicked do not repent even at the Gates of Gehenna."

The Road to Hell

It turns out it's not easy to get to the uttermost depths of Hell. No Jewish taxi will drive there because strangers and Israelis are frequently stoned by embittered villagers. So hire an Arab taxi to drive down a service ramp, and then along the filthy trek that is Gehenna. Even the Arab driver will resist. Pay extra.

When the taxi can proceed no farther down, get out and scramble up a short rocky ridge. Two scruffy Arab boys across the way may jeer, wagging their fingers and shouting warnings to turn back. Disregard them, and walk to the edge of the cliff face.

There you'll find a great cave, its arched entrance guarded by six-foot-high thorn bushes. Impenetrable. Urine from the unsewered toilet in the convent above--the very convent that legend claims to be founded with Jesus's blood money--trickles from its open pipe down the escarpment and over the cave's entrance. Feces from man and beast lie everywhere. Rodents dart and snakes slither.

Here is the lowest point of Gei Ben Hinnom. The absolute pit.

On either side of the cave entrance, hung from spikes driven into the rock, are twine-strangled jackals, angry snarls frozen in death.

This essay is based on research conducted for Edwin Black's recent apocalyptic novel, "Format C:," published by Brookline Books.