Location from Fullmetal Alchemist by Hiromu Arakawa
A vast network of tunnels beneath Amestris dug by Sloth over decades, forming the lines of Father's nationwide transmutation circle and connecting to his lair beneath Central.
Enormous, rough-hewn tunnels stretching for hundreds of miles underground. The walls are raw rock, the air is stale, and the scale is inhuman — clearly dug by something far larger and stronger than any human work crew. At the center lies Father's cavernous throne room, a sterile white space of pipes and conduits.
Also known as: The Tunnels, Father's Lair, The Underground, Beneath Central