Lord British's Amulet

Provided by Little Stinky Dragon:

Lord British went down some falls in Spiritwood and entered the Underworld. That’s where we have to go. Spiritwood is located southwest of Britain and east of Skara Brae. Be sure to have a VAS REL POR scroll on you. Find the huge falls and grapple down.

Once you're down there, make your way through the various rooms and find Lord Britsh's Amulet stuck in a wall, where you can easily plug it out. Afterwards use another gate scroll (Vas Rel Por) to get out of there fast.