Hey, all. I'm having a problem with the Gaulder Amulet quest. I've collected two of the fragments and I'm trying to get the third at the excavation site in the north-east. The problem is that I can't find the key to the door. I've searched every location related to the quest, and nothing turns up. I've searched every container outside the ruin and nothing still. I have a feeling that the quest script is broken as the area around the excavation site is deserted. The only people I can find in the area are a couple dead bandits and a dark brotherhood assassin I killed. Am I not looking hard enough or is there a problem with the quest? Thanks in advance!

I believe you can only unlock the door to that place by going the Mage's route, by doing the mage questline which eventually leads to "Under Saarthal".

You need to join the College of Winterhold. It's the first mission you go out on.

Start the college of Winterhold quest line and around one of the first quests, you have to go to the excavation site and it becomes unlocked.

get into the college of winterhold and start the mage quests to gain access

Yep, it's down side for some quests...you have to join particular guild to get access to some certain areas or quests >.<