Hellways

The hellways are a collection underground tunnels and complexes spread all throughout the world, underneath the surface. They are home to the devils and the elves, which feed on the souls of the dead which sink through the earth. It is possible to navigate through the hellways and come out on the surface somewhere else without the dangers of coming across undead, but passage must be negotiated at a hefty price with the devils.
While there are not typically undead within the hellways, other dangerous monsters have taken refuge here while it is too dangerous on the surface. The devils can easily handle most dangers encountered on the hellways, but travelling in secret or without an escort is not advised.
There are currently projects to build rail networks through the hellways, but so far only limited locations have been linked up.