Anor Londo

Anor Londo was a great City inside the lands of Lordran, but now resides within the Boreal Valley.
== The City of The Gods ==
When the wielders of the Great Souls succeeded in defeating the Dragons, the Lord Gwyn wanted to create a city that would be fit for the Gods within his new lands. There he founded the great city of Anor Londo, commonly known as the City of the Gods and served as the throne for Gwyns rule. When Velka, the wife of Gwyn had several children they were all classed as the highest Gods of all. But when Velka was taken by Seath for himself, she bore twins , Priscilla and Yorshka, both crossbreeds and whilst Yorshka remained a secret, Priscilla was not so lucky. Yorshka was kept secret and hidden below the Cathedral by Gwyndolin, her half brother where she remained.
=== When The Flame Fades... ===
When the First Flame began to fade, the Gods began to become nervous of the incoming darkness the world was beginning to plunge into, as did Gwyn. Gwyn decided to take it upon himself to use his body as kindling to resurrect the flame and renew the burning of the fire, prolonging its fading but not before splitting his Lord Soul and giving it to his children.
When the Flame was linked however and following the banishment of Gwyns Firstborn, the Gods decided to leave Anor Londo including the Princess of Sunlight and Gwyns daughter, Gwynevere leaving only Gwyndolin as the ruler of Anor Londo. However Gwyndolin's sickly nature made him believe that he didn't deserve the throne and so he constructed an illusion of Gwynevere to rule in his place, making it appear that Gwynevere had never left and that she was ruling Anor Londo.
Gwyndolin also ordered the construction of a Fortress, built by a man called Sen, to serve as the entrance to Anor Londo and as a way to prove their worth to enter the city of the Gods. Only later on was Sens Fortress sealed off and to provide an extra challenge for the prophesised 'Chosen Undead', there was a construction of two bells, one inside of what became known as the Undead Burg and one deep below the earth close to Izalith and constructed by one of Izaliths daughters, Quelaag. Once these bells were rung, the fortress was open to the Chosen Undead and also awakened the Kingseeker Frampt, who promised Gwyn that he would help the next Lord of Cinder link the fire.
=== The Chosen One Cometh ===
When the Chosen Undead arrived in Anor Londo, they were met with fierce defenders of the city, including the remainder of the Silver Knights of Gwyn. But upon entrance to the Cathedral of Anor Londo, the Chosen Undead discovered that Dragonslayer Ornstein and the Executioner Smough were guarding something. In a great battle, they manage to overcome both Ornstein and Smough and were able to make their way to the illusion of Gwynevere, who bestowed upon them, the Lordvessel, the item necessary for becoming the next Lord of Cinder. 
The Chosen Undead saw through the illusion however and decided to break it by slaying Gwynevere revealing the truth and the state of Anor Londo. The City of the Gods was then plunged into darkness, having been under an illusion so long, revealing its true fate, one under an eternal moon, likely thanks to Gwyndolins nature of being born under a full moon.
=== Becoming the Boreal Valley ===
Over time, the great city began to move and distance itself away from the rest of Lordran due to its magical nature. Due to it being under perpetual moonlight and was surrounded by mountains it became known as the magical Boreal Valley, with Anor Londo being situated inside it. As the city of Anor Londo became to sit in a state of disrepair and much of it was brought down and or fell to the ground below. In its place, adventurers and inhabitants of the city began to construct it anew, under the full moon and named it Irithyll. 
The date in which it is built is unknown, but it was certainly after the Chosen Undead linked the fire in 287FY and long after, but also some time before 1302FY, when Saint Aldrich hailed from there and set out into the world. Aldrich originally said that he was a descendent of the Gods of Anor Londo, which would imply his is an ancient being considering the Gods have not resided there in a long while. This did not stop him gaining a great following however, as he proclaimed himself as a man of the Way of White. But his thirst for power grew too much and he became a cannibal, feasting on many humans whilst being watched over and followed by his Archdeacons. Aldrich would also go on to marry a woman called Rosaria, supposedly the child of Gwynevere of which Aldrich had children to, some that he would devour and some which would escape his clutches and then imprisoned her within a cathedral in Irithyll. Aldrich then grew to so much power that he became a bloated sludge of mass, powerful enough to become a Lord of Cinder of which he took up and linked the flame in 1335FY. Rosaria then fled to Carim, leaving her children in Irithyll. Aldrich's deacons then created a Cathedral dedicated to him, located in the lands of Lothric, in which it is named after Aldrich, being called the Cathedral of the Deep. The dregs of all of Aldrich's killings and cannibalisation are all brought to the Cathedral and are left to fester.
=== The Rule of the Pontiff ===
Eventually a man called Sulyvahn, a Corvian who hailed from the Painting of Ariandel ventured out of the painting and to Irithyll to gain its knowledge and there discovered an ancient civilisation, unknown to the world called the Profaned Capital and claims the power he found there for himself, subjugating the Profaned Capital and Irithyll alike, naming himself Pontiff Sulyvahn. He battled Gwyndolin and Yorshka for rule over The Boreal Valley, with Sulyvahn coming out of it the victor and imprisoning both Yorshka and Gwyndolin within the Great Cathedral of Anor Londo. Two of the children of Rosaria, one named Vordt and the other, an unnamed girl, were made into Outrider Knights, though this was not a courtesy. 
The Outrider Knights served as a force that would be sent out of Irithyll to do Sulyvahns bidding and were given magic rings that slowly made them lose their mind. Vordt transformed into a beast like animal, causing him to walk on all fours with his armour twisted into his image. The Unnamed Girl was forced to become Sulyvahns Dancer and slowly went mad, her armour that was gifted to her began fusing to her body and she began to use twin swords that mimicked Sulyvahns and turned into a wild frenzied animal, her battle technique becoming that of a dancer.
=== Aldrich Returns ===
When Aldrich was revived as unkindled ash as part of a mass-resurrection by the Firekeepers to link the flame, he like many of the others abandoned their duty and instead returned to their lands. Aldrich is awakened in his coffin in the Cathedral that was built for him where he then has a vision. A prophecy of a deep sea that would overtake the whole world and swallow it, before realising he wanted to become the Lord of this Deep Sea world. In 1665FY he then gathered all his followers and deacons before marching on Irithyll and battling Sulyvahn. He succeeded in this fight with Sulyvahn then being under his command. Aldrich created a set of dolls and began to seal off the Boreal Valley with a great magical field, with only the wielders of the dolls having access to the valley. He then ventured into Anor Londo to start devouring Gwyndolin slowly which in turn put him into a deep slumber as the devouring process starting working.
=== The Devourer versus the Unkindled ===
When the Ashen One had been revived as part of a mass resurrection of Unkindled, part of his quest was to bring slay Aldrich and bring him back to his throne, in order to become a Lord of Cinder. As his journey into Irithyll proceeded, he met one of Aldrich's children Anri and her protector Horace, who at some point had tried to kindle the first flame and failed, but were subsequently resurrected as an Unkindled in an attempt to bring her fathers remains back to Firelink Shrine. They then joined up with the Ashen One and ventured into Anor Londo together.
As the Ashen One and Anri enter the Great Cathedral of Anor Londo and subsequently its Great Hall where the Chosen Undead once battle Ornstein and Smough, they discover Aldrich, who had been consuming Gwyndolin for long enough now to fully take his power and appearance and so a fight ensued. Whilst the devourer of Gods possessed great power, as did his daughter, who over the years in Astora honed her skills and now had great fighting spirt and strength. With the Ashen One, they manage to slay Aldrich, but Anri unfortunately perished during the fight. The Ashen One then brought his remains back to Firelink Shrine and with Aldrich's death, Gwyndolin escaped his horrific ordeal, allowing him to finally be at peace.