- "Lia Fail means 'The Stone of Destiny.' This city was a holy ground of the Tartarga people before the Great War, but it was destroyed by the Carmina Gadelica forces which did not like the idea."
- — CC Corp —
Lia Fail, located in the Omega Server, is a Root Town that holds the highest level areas in The World.
Lia Fail is a city of shrines to the various Gods of The World and is fiercely protected by the most powerful adventurers from the fierce monsters that prowl outside of its spiritual shield. During the War of the Gods a gigantic cannon was built in Lia Fail. Using energy siphoned from the Goddess Aurora the gun fired into heaven and destroyed the Gods. However the force of the blast also destroyed Lia Fail, which is why it is not accessible in The World R:2.
During the events of the Games, the Omega Server became highly unstable and was replaced with a mirror server created by Helba. The root town for this server was modeled after Net Slum. Corbenik, the final Phase attacked the .hackers here. During the fight CC Corp attempted to shut down the server, Junichiro Tokuoka and Mai Minase managed to switch the server onto another mirror at the last minute, saving the .hackers's lives and allowing them to win the battle.
- Lia Fail takes it's name from the ancient coronation stone of Ireland's High Kings, Lia Fáil.
- Lia Fail's structure is a reference to Stonehenge and the Medieval period.
- Lia Fail is only displayed during entry of the protagonists (the beginning of .hack//Quarentine), but was never explored due to instability caused by viruses and wave.