Inverted City Megin Fi

Inverted City Megin Fi (背面都市　マグニ・フィ, Haimen Toshi Maguni Fi) is a Lost Ground located above the Battlefield of Coite-Bodher. It can only be accessed through the Sign there.

The World R:2 Official Story
Megin Fi is a city built atop the sealed form of Mag Mell, the war dragon of the gods. Defeated by humans and turned to stone during the battle of Coite-Bodher, a great city has since sprung up on its back.

.hack//Roots
Searching for the Key of the Twilight, the Twilight Brigade activated a Sign to Megin Fi from Coite-Bodher. As Ovan entered the city alone the rest of the Brigade began fighting against Ender and the Black Ops of TaN unaware that they were doing just what TaN wanted. As the battle raged below Ovan walked into a trap set by Naobi and was captured. Their mission complete Ender and the Black Ops escaped leaving the Twilight Brigade to deal with the sudden loss of their leader.

.hack//G.U. Games
Ovan escapes here after revealing his arm to Haseo. Haseo follows and confronts him. Ovan says that this place is where "everything began to go downhill", but "there is no going back". Haseo defeats Ovan here, and Yata appears, telling Haseo that the Lost Ones still haven't awakened.

Trivia

 * In Redemption, Inverted City Megin Fi is not accessible.