Where is this Underworld place?

I have the map and book. But cannot see it anywhere. Is it something that is only available once you finish the game?

I've also heard of the Fissure of Woe?

Semms like there is way more to this game than meets the eye.

You can get to the Underworld and the Fissure of Woe from the Temple of the Ages. Just walk up to either the statue of Grenth (for underworld) or the statue of balthazar (for fissure) and kneel. A ghost will come up and you can give him 1k for access. However, you need to be level 20 and ascended. You can only enter when your country has the favor of the gods.

Thanks