Whether there is "fire" or not, suffice it to say, it will be a place of great suffering.
Years ago, I read the Diary of Sr. Faustina, a recently cannonized saint. She was polish nun who received apparitions and locutions from our Lord. She recorded in her diary that Jesus took her to Hell so that she could warn sinners. I'll have to go get it for the exact wording but the two things I remember about it were, one, many souls that were there, did not believe in Hell when they lived on earth, and second, she saw many "pits of torture".
I remember getting the chills after reading it.
Also, you should also google "children of Fatima" they had a vision of Hell and described an eternal fire so terrifying, that after the vision, they begged the Blessed Virgin that our Lord would bring them to heaven, it so terrified them. I'll try and find it.
Okay, found it, here is a snipet...
At Fatima, the Blessed Virgin Mary told the three child seers that many souls go to hell because they have no one to pray or make sacrifices for them. In her Memoirs, Sister Lucy describes the vision of hell that Our Lady showed the children at Fatima:
"She opened Her hands once more, as She had done the two previous months. The rays [of light] appeared to penetrate the earth, and we saw, as it were, a vast sea of fire. Plunged in this fire, we saw the demons and the souls [of the damned]. The latter were like transparent burning embers, all blackened or burnished bronze, having human forms. They were floating about in that conflagration, now raised into the air by the flames which issued from within themselves, together with great clouds of smoke. Now they fell back on every side like sparks in huge fires, without weight or equilibrium, amid shrieks and groans of pain and despair, which horrified us and made us tremble with fright (it must have been this sight which caused me to cry out, as people say they heard me). The demons were distinguished [from the souls of the damned] by their terrifying and repellent likeness to frightful and unknown animals, black and transparent like burning coals. That vision only lasted for a moment, thanks to our good Heavenly Mother, Who at the first apparition had promised to take us to Heaven. Without that, I think that we would have died of terror and fear."
Here:
"But I noticed one thing: That most of the souls there are those who disbelieved that there is a hell." (Diary 741)
People choose what they will believe and what they will not believe, but even the ancient pagans knew of Hades.