J´ai fait une petite recherche sur le net et un bouquin dans le jeu parle de cet endroit :
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Oblivion Explorer´s Guide
Tomas Bloodmark´s complete guide to the dark places of the earth and the cities and towns of Cyrodiil.
Beneath the ground in ancient catacombs and Ayleid ruins lie untold treasures and unfathomable dangers. This book contains the vital information of all the locations I have explored in my short but eventful life, as well as my recommendations on where best to equip yourself for future explorations. It is, of course, a work in progress, as there are no end to the subterranean mysteries of Cyrodiil...
Fanacesecul (Ayleid Ruin)
Small undead lair.
Welkynd Stones: 8
Varla Stones: None
Loot: Good
Traps: None
Noteworthy features: None
Location: SSW of Wawnet Inn, NWW of Imperial City Waterfront, due North of Fort Virtue
Fort Virtue (Abandoned Fort)
Small undead lair.
Loot: Poor
Noteworthy features: None
Traps: Two dart traps in room with ghost on raised platform
Location: West of Imperial City Waterfront, South of Fanacesecul, South of Wawnet Inn
Sideways Cave (Cave/Ayleid Ruin)
Large mythic creature den.
Loot: Good
Traps: Cave-ins
Noteworthy features: Subterranean lake, waterfall, joins up with buried Ayleid ruins
Location: Directly West of the tutorial sewers exit
Vilverin (Ayleid Ruin)
Large bandit, undead and necromancer lair.
Welkynd Stones: 22
Varla Stones: One
Loot: Bountiful
Noteworthy features: Secret doors, Khajiit killed by necromancer mini-story, Ayleid statue in the center of the swinging blade trap corridors
Traps: An intersection of corridors filled with swinging blades
Location: Directly ahead when you exit the tutorial through the sewers
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La source :
http://elderscrolls.blogspot.com/2006/03/oblivion-explorers-guide.html
Par contre le "It is, of course, a work in progress, as there are no end to the subterranean mysteries of Cyrodiil..." pourrait laisser penser qu´il faudra attendre un mini add on...