Across the Golden Gate Bridge from San Francisco are the Marin Headlands. It's a protected area run by the national park service full of trails and stunning views of the vast ocean outside of the bay, the Golden Gate Bridge and the city of San Francisco.
It's a great place to go to see the city and the bay but there's also some surprising attractions such as a light house and even old military defense bunkers and missile launching sites (I had no idea there used to be nuclear missiles stored here and ready to launch!).
Here's the lighthouse-
To get to the lighthouse you get to walk through a tunnel that was hand chiseled in the late 1800's.
View from the lighthouse.
Here's the missile! They're stored underground and are raised up by an elevator. The park ranger tour lets you go underground and watch the missile go up in the elevator. It's crazy to be able to see San Francisco and this at the same time, I had no idea this was over here to protect our shores. This is now a tourist attraction and these aren't active weapons.
Have you ever explored the Marin Headlands?