The river of the Dead is housed in a realm near the middle of the Building. The entrance being above water, and lots of it, if one has transportation they can reach The City of Lights. Once a great hub of commerce, the city was somehow captured by the New Day company and placed within the Shadow realm.
Due to the Sinister nature of The Styx, the city itself has begun to deteriorate in some places, and despite retaining the glow of the lights for which it was named, in some places the city has gone dark for good, and many an adventurer has ventured into the Dark and not returned.