The Apothecarium lies in the southwest corner of the Undercity. It is the home of the Royal Apothecary Society, a large-scale organization of undead led by Master Apothecary Faranell and dedicated to eradicating the "infestation of humanity" from Lordaeron. This is where the Forsaken work to brew their newest plagues and poisons, as well as creating more powerful abominations to serve in their armies. It is the center for alchemy training for the Forsaken. Forsaken medics such as Vellcinda Benton also studied here to learn the science of tissue and organ transplants.
After the Cataclysm, Koltira Deathweaver was captured by Sylvanas Windrunner. During the Burning Legion's third invasion, it was revealed that Koltira was held captive in the Apothecarium. Thassarian and the Deathlord of the Ebon Blade infiltrated the Apothecarium only to find it abandoned. They killed Gurgoth and freed Koltira.
In the RPG
This area is the domain of Master Faranell and his alchemist minions. Located in Undercity's bottommost depths, the Apothecarium radiates evil and malice. The lab is full of horrors. Rickety tables are covered in bubbling, steaming potions, dripping candles and acrid beakers. Shelves hold weathered tomes, bizarre skulls and strange creatures suspended in jars of green liquid. Squealing, distorted experiments thrust tentacles, pincers and eyestalks out of iron cages, begging for release.
The name Necropolis mentioned in may be an alternate name for the Apothecarium, though originally the Undercity was called "Necropolis" in early concept maps for World of Warcraft. The quest text may be a remnant of the alpha stage considering its ID.