In the far, ice-covered northeast of Serpent Isle, deep inside the mountains lies the ancient Ophidian city of Spinebreaker, the city dedicated to Order. It opposes Skullcrusher -- the city of Chaos.
In the time of Ultima I, the dungeon was known as Spine Breaker, and wasn't that remarkable. However, after the three serpents appeared, the city of Order was built within the dungeon, housing at its most northeastern point the Shrine of Order. After the War of Imbalance was over, the followers of Order used the Wall of Lights in Spinebreaker to leave the Serpent Isle for a place unknown. Afterwards, the city became forgotten in the icy wastelands.
It wasn't until much later, when Batlin tried to use the Wall of Lights there, to enter the Void. The Avatar followed him, but in the end the Banes of Chaos were set free.
Leaving the empty city, the Avatar left it to again fall into the mists of history.