In Sunnyvale (town outside of Megaton) there is a ruined house. It has two suitcases sitting outside the door. The eyebot travels back and forth on the street in front of it. If you go up the road you will reach Vault 101. In the ruin are cellar doors that are locked and require a key. Where is the key? I don't remember this on the PS3 version of the game.

It's a DLC thing later on.

That's unlocked during one of the Broken Steel quests - you'll have to finish the main quest first.

Thanks! Now I know why I didn't see it before.

which quest? I have finished the main quest of broken steel a few times. but i have yet done a quest that uses that door.

The quest is named Holy Water - talk to Scribe Bigsley at the Jefferson Memorial to get it, but only if you didn't blow up Megaton. You can't get the quest if you did.

thanks