Big Castle Ruins:

5,000 Smithing XP
In the High Wilderness (Level 47) far east of the Demonic Ruins

Rogue's Castle:

10,000 Thieving XP
Portal is 3 cells east of the broom leaning on the wall, outside castle in the backyard.
While in the spirit world, close both jail doors inside the Rogues Castle.
Return to the regular world and tell the rogue in the cell that you are helping him escape.
Afterwards you can find him south of Varrock's archery shop where he will buy
unenchanted rings for their high alch value.

Chaos Altar:

5,000 Prayer XP
In the Level 12 Wilderness, south of Clan Wars Arena. Includes a Spirit Person that will tell
you about the God Wars and how Guthix interfered - need Amulet of Ghostspeak to talk to him.

Dark Warriors' Fortress:

10,000 Defence XP
In the Level 20 Wilderness, west of the Bounty Hunter Arena.
Invisible portal is in the centre of the courtyard.
Includes Level 129 Tormented Wraith that can be attacked if you are wearing
Full Black Armour (Helm, Plate, Legs, weapon, and shield unless black weapon is 2h).
See – “Tormented Wraith” at the bottom for more information.

Ruins

5,000 Farming XP.
North-west of Clan Wars, the Quest start area

If you lose Jennica's ring, search the rubble 1 square east of the portal.

“Tormented Wraith”