In Heirs to Merlin there are two fallen covenants.
Stellasper
This one is is Scilly. I suppose I should have looked up more Sicily folklore before I wrote this. Stellasper was a Criamon covenant founded in 1025, and everyone vanished in 1163. The name means “through the stars” or possibly “during the stars”. I presume it’s an astrological sept.
Sursum
Was on the northern coast of Cornwall. Presumably it is a mine. It was destroyed in 937, and its Tytalus was one of the first signs of the Corruption. The name is an abbreviation of “subversum”. Presumably it’s a mine, and one of those stupid things where Infernally-aligned characters can’t help but do the Riddler thing. So, this is a dungeon, presumably.
Games From Folktales 