The Undercity is the capital city of the Forsaken undead of the Horde. It is located in Tirisfal Glades, at the northern edge of the Eastern Kingdoms.
Far beneath the ruined Capital City of Lordaeron, the royal crypts have been turned into a bastion of evil and undeath. Originally intended by Prince Arthas to be the Scourge's seat of power, the budding "Undercity" was abandoned when Arthas was recalled to aid the Lich King in distant Northrend. In Arthas's absence, the Dark Lady, Sylvanas Windrunner, led the rebel Forsaken to the Undercity, and claimed it for her own. Since taking up residence, the Forsaken have worked to complete the Undercity's construction by dredging the twisted maze of catacombs, tombs, and dungeons that Arthas began.
The Undercity is an extension of the crypts and dungeons originally beneath Lordaeron's capital city. The Forsaken dredged out complex catacombs and caverns below the Ruins of Lordaeron. The place is dark, smells of corpses and has an evil feel. Spiders, oozes and other subterranean creatures occupy the distant passages. Rivers of poisonous sludge flow through all avenues of the vast Undercity. The toxic fumes and fetid odors permeating every corner of the stronghold have made it a place almost unbearable for the living members of the Horde. Yet for Sylvanas and her cursed followers, the Undercity has become a much-needed refuge in a world where her kind is still feared and hunted. It is drastically different from any of the other capital cities for the Horde. Unlike Thunder Bluff and Orgrimmar, which are at the surface and often the sites of multiple festivals, the Undercity is dark, dreary, and cold. The Forsaken, however, are known for holding two festivals, Hallow's End and Pilgrim's Bounty. The Forsaken chose to manly live below ground, with limited Forsaken activity in th ruins above.
The city is made up of roughly symmetrical quarters arranged around a circular center.
Since the release of The Burning Crusade, players with the expansion are able to access an Orb of Translocation to the Silvermoon City palace, making it easy for anyone to travel between the two cities without having to go through the Plaguelands. The translocator works both ways. The Undercity orb is located in a newly opened city section west off the main part of the Ruins of Lordaeron. The translocator teleports you to the Inner Sanctum of theSunfury Spire within Silvermoon City.
It cannot be used by the Alliance.
Although the memorial to King Terenas appears to be a stone tomb, it was shown in Warcraft III: Reign of Chaos that after his death, Terenas was cremated. Furthermore, the urn containing his ashes was used to resurrect the Lich Kel'Thuzad. It is unknown what happened to the King's remains after this point. The memorial was crafted by the Alliance humans who once inhabited the old city, who risked everything to ensure that the memory of Lordaeron's last true king would not be forgotten.
When you stand in the Throne Room, at least in the center of the circle on the floor, with the ambient sound turned all the way up, in the background noises you can hear small clips of Arthas, Medivh, andKing Terenas. For those who wish to hear this without venturing into the Undercity, the ambient sound file is located at (WoW Directory)\Data\Sound\Ambience\WMOAmbience\UnderCityThorneRoom.wav.
If you look closely on the floor of the throne room, near the foot of the throne, you can see a small trail of blood that was left by the crown as it rolled onto the floor.
By the same token, in the outer hall leading into the throne room, one can hear the celebration of Arthas' return by Lordaeron's citizens. The floor is littered with dead rose petals, the same ones seen showering Arthas during the cutscene in Warcraft III.
When standing by the bell outside of the throne room you can hear it ringing.