The Temple of Death

Welcome, faithful one, to the Temple of Death.
This huge subterranean place of worship is built deep below the castle. Since the time of it's initial construction, damage and weather have led to the submersion of various parts of it under water. Thus, this temple is reachable only by boat, and the waters that surround it are filled with many foul escapees from the summoning lessons of the school above.
The labyrinth like series of halls, all now flooded, were designed to trick those attempting to reach the inner sanctum of the temple. Some are over forty feet wide, sprawling galleries with ceilings that disappear high into the shadows above. Others are only large enough to admit the smallest boat. This is further complicated by the changing of water levels, which occurs almost every week, forcing temple-goers to re-route their journeys.
Upon reaching the temple itself, which is always above the level of the water, you are faced with a great, black monolith, protruding from the waters around it like a gothic island. It is huge, as big as a cathedral, and covered with grotesque gargoyles and serrated spires. The most obvious thing about the temple is its colour. The entire temple is black, being crafted from obsidian, granite, slate and iron all of the deepest black, so that the temple appears to be a monstrous shadow.
Within it's ebony walls, the outer sanctum is the first perimeter. Composed of numerous lesser shrines and the abodes and workshops of the Black Priests, this is the most known portion of the temple. Dark wizards and witches from all over the world make long pilgrimages to this temple to appease Death itself. Also in the outer sanctum are the tombs. Each tomb houses the corpse of a great Dark sorcerer, and it is the desire of every practitioner of Dark Magic to one day be laid to rest within one of these tombs. Each is a focal point of dark power, a nexus of energy within which the soul of the dead wizard may retain its consciousness. Many journey to the Temple merely to consult these shades on matters of magic and power.
On the south side of the Temple's inner walls lies are the Black Gates. These towering iron doors are studded with precious onyx and jet carvings, all depicting Death in His various guises and forms. These gates are guarded at all times by the Temple Wights. These grim, undead knights wear moldering armor and clutch rusting blades in their bony hands, their empty sockets containing only a magical red glow. It is said that Death Himself raised these knights from the dead to forever guard his abode. Whether or not this is true, the Wights have prevented those not allowed from entering the Inner Sanctum for as long as any can remember, and are deadly in their efficiency. Through the black gates lies the Inner sanctum, which is made up of only one vast chamber. On its north wall stands the five hundred foot high Altar of Death, and in the centre of the room lies the Conclave. It is here that the legendary Four plot their dark deeds, forever watched over by Death Himself, the Great Master.
The walls are lined with huge carved stone sarcophagi, each holding the remains of a great wizard trapped forever in and endless cycle of torture. This dark energy generator is known as the Infinity Circuit, and allows the powers of dead wizards to be eternally tapped. Four of the sarcophagi hold the founders of Hogwarts - Gryffindor, Slytherin, Hufflepuff and Ravenclaw, bound for eternity within the circuit, doomed by Death Himself to provide power for His followers. It is said that, with the correct spells, one can open portals to the places which these great wizards occupied in life.