The Dread Citadel

Naxxramas. Originally released as the final raid instance of Vanilla World of Warcraft, it was the hardest thing players could hope to tackle at level 60. With fourteen bosses in five massive wings, it would go on to be remembered by veteran players as an excellent and highly rewarding experience.

An interesting note about this dungeon, most of the items acquired here were actually enough to wander into Karazhan with, surpassing even most of the rare items from dungeons. Also, the Tier 3 sets were nine pieces instead of the usual eight- a ring was added to the mix!

Unfortunately, many players had not been able to experience the full wrath of Naxxramas, and many guilds had not even completed it, as there were six months to do so before the release of Burning Crusade. Six months wasn't enough time for raiding guilds back in the day, as raid bosses took much longer than a few weeks to develop and perfect strategies on. This also led to a retcon of the raid, as it would later reappear in Wrath of the Lich King as the introductory raid with a new story.

In Wow's third expansion, the entirety of Naxxraamas was re-tuned for both 10-man and 25-man groups, a lot of trash mobs were removed, replaced, or rearranged for smoother traversing. Bosses still retained MOST of their original abilities with relatively minor tweaks, such as damage outputs and mechanic changes to account for a smaller raid group. The original Naxxramas was tuned for 40 people.