The Luminarium was constructed by the Seraphs to serve as an atonement for their role in the Battle of Isonkast in which the Father stripped them of their wings. The Luminarium was designed to resurrect life spheres. Under the Father's orders, the Seraphs who maintained the structure are to serve any who reach the Luminarium with a life sphere in hand regardless of their affiliation including that of Hell. Due to being a holy place, no living being can draw blood in the Luminarium and doing so they will lose all access to the power of resurrection.
Following the defeat of the Dark Lord, the Father withdrew from the physical realm and placed his essence inside a life sphere, which is then stored in the Luminarium. For many ages, the Maykrs and other supplicants came to the Luminarium to pray for intercession. The Father's life sphere remained there until the Seraphim stole it and hid it away from the Maykrs.
Following the downfall of Urdak to Hell, the Doom Slayer traveled to the Luminarium with the life sphere of the Dark Lord in order to revive and kill Hell's ruler. The Slayer was temporarily stopped by the Seraphim from entering the Luminarium, but was able to defeat him in combat and proceeded to resurrect the Dark Lord.