Build an enormous dark Nether hub w...

Build an enormous dark Nether hub with a colossal central portal chamber, massive fortified walls, grand radial tunnels leading in every direction, huge arches, layered bridges, lava falls, suspended walkways, intimidating towers, and a brutal blackstone/deepslate/red palette. Make it feel like an ancient imperial fortress built inside the Nether, with extreme scale, strong symmetry at the central hub but varied architecture around it, deep wall thickness, dramatic verticality, and absolutely no plain boxy rooms.