Marble and greenish textures used for this one, symmetrical pretty much.
Credits:
Pikkuhippi; testing, editing (dehacking) Wirtualnosc; testing CodeImp; Doombuilder ID Software; Doom2 Also credits to this person who made this awesome remix MIDI of MAP30 (I don't know who is the creator, because I got this one from my friend, so whoever knows; PM me)