I did that once with one of my cousins when we were both pretty young - probably around 1977. It was still pretty safe back then and we didn't have to watch where our feet were going. We spent a day wandering around.
I did it with co-workers back in the 80s. We were all new college graduates working our first job, and we were on travel in the Bay area. It was a fun time, and I loved SF back then