As of March 25, 2008 - Karazhan no longer requires attunement, but the key is still necessary to open the doors. Archmage Alturus of The Violet Eye just outside the tower itself.

Do you need attunement for Karazhan?

Karazhan is the first raid dungeon requiring an attunement quest in The Burning Crusade. The questline for it is rich in lore and offers just the right balance between being too long and being too short.

Can you enter Karazhan without key?

You dont need the key to run kara but you need the key to open the gates. So if you have a friend who has the key you can still run it, if not, you can easily solo the quest chain at 80. Bear in mind, the quest chain has you running many of the Outlands instances.