The Soul Tower from the name itself, it contained souls. The source of power of the tower were gathered souls, in order for the creatures to be able to live, they were all formed from the remnants of the deceased. Unknown to Zero, each of the monsters that he had been dealing in the tower were alive due to human souls - stray souls and souls of the dead that were trapped here, unable to go to the afterlife nor the river of reincarnation.
Presently, he was in the third floor and instead of the usual damp or dark place, it was oddly full of shining gems. The place was like in a grand mansion, marbled sapphire floor, the walls were decorated with vibrant glimmering jadeite and the ceiling had a luxurious epicurean chandelier hanged atop.
Only one word you could describe. Extravagant.