Whoever populated the winding tunnels of the Subterranean City before left behind a number of signs to guide you through them, marked only with simple iconography. Most of them are straightforward: this tunnel to this square, another to this statue, a third to that landmark. But there are some that don't lead you so directly, and are marked with less straightforward symbols. In particular, some of the signs are clearly marked with a lantern. The Lantern? It's hard to say.

For anyone curious enough to look, there might be insight to be had about The Ferryman, and about their relationship with the ones who came before you.