So, this is a map of the city with some of the underground tunnels drawn on top. Caelum has hundreds of tunnels running beneath it, most of which are no longer 'officially' in use... but in the past few decades, they've become heavily used by criminals to navigate the city undetected, hide loot, and create secret hideouts. Some of them are abandoned mining tunnels, train tunnels, sewer pipes, or just rough dirt passageways.

The tunnels are basically a maze. Claustrophobia or a bad sense or direction would serve you poorly down here, and it's not unusual for people to get lost and die underground.

This is only supposed to be a /very/ rough map, and isn't intended to show every tunnel or the exact layout of them. It's more to give you a general idea of what lies beneath Caelum's streets. The black lines are smaller tunnels, the yellow areas are larger tunnels, and the black dots are the above-ground entry points (currently, North Caelum seems to have the most).

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The entry points are often found in alleyways, abandoned buildings, and other places where they're harder to find. They might be hidden under piles of rubbish, under floorboards, or behind trapdoors. Seasoned criminals often know where many of these entry points are located, and can use them to access the tunnels from almost anywhere in the city.

The blue area is the hideout of Mason's werewolf pack. It's a large cavern where they store all their stolen goods/money before deciding who to give it to. The hideout is hard to find, due to the maze-like passageways that surround it. (The werewolves have memorised the routes, often using each others' scents to navigate to their hideout.)

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@Alkaline - The orange area is where I imagine the train tunnel Althea and Den entered to be, or at least the rough location of it. The black dot would be the entrance and the blue tunnel is the one they ran down after fighting the werewolves.

All of this is very much a WIP and subject to change, but hopefully this will give you somewhat of an idea of what the underground is like. XD

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Oooo yes! This is very helpful, I love maps, you make me want to try some now lol.