Modern astronomy has put paid to the notion that heaven and hell are anywhere out there, relegating the abodes of the immortals and the dead to another plane of reality that's inaccessible from our universe by natural means, if not entirely imaginary. In older and simpler times it was still conceivable that you might climb a mountain and find the gods, and that on the far bank of a dark and sluggish river lay the dwelling place of those who no longer belonged among the living.
Thus it is in the Vulcanverse, where Hades's realm is a physical location. There are things there that do not sleep. Companions may desert you at the gates. Food in your backpack will rot and flowers wither. Even so one can simply walk into the land of death, a region that Homer tells us is "so dim, so dark, so loathsome; abhorr’d by men and dreadful even to the gods."
But where there is danger there are great prizes to be won, and glory awaits those courageous enough to venture among those "mouldy mansions so ghastly grim that even the gods shudder to think of them." So be sure to have the Hades gazetteer to hand (to be found here and here). And another resource that will be useful to explorers of the Vulcanverse is this list of tickboxes for books 1-4 so you don't have to mar your copies. (Thanks to John Jones for that.)
