Fuad's Cellar is a small dungeon that can be found in Howling Plateau in Act II of Diablo III.
Inside, Fuad the Cannibal is waiting for the player. A Chest is also found there. This seems to share a rotation of non-event modes in the area. Look for some cultists in a spot that has stairs receding down into a small depression of land. When you get near a cellar door, you will hear sounds coming out of it and see a speech bubble over it.