A distant early warning for Oakland

When I was an undergraduate in college, my best friend and I took a long automobile trip one summer. We decided to drive as far north as we could, from Massachusetts. While in the middle of nowhere around Hudson Bay, a hill appeared out of the fog. It had a dusty road leading up to the top, so we decided to explore it. To do so we had to pass through a tall chain-link fence, but the gate was open, and no one was around.