The Old Gotham Subway is an underground series of abandoned subway tunnels located underneath Gotham City in the Burnley district.
Following Brainiac bottling the majority of the Diamond District, including the Iceberg Lounge, Penguin relocates his headquarters to the subway tunnels and begins manipulating the gang war in Gotham, evoked by the Joker, to his favour.
Be wary of the extremely dangerous Soul-Infused Corpses in the area.
Learning of Penguin's plans, Two-Face, due to a good-side flip of his coin, informs the new heroes of them and leads them to the Penguin's lair in the old subway tunnels.
Following their success, Two-Face takes over the lair for his own purposes.