To peter1892: Its called Sutro Tower...

  • and is in a neighborhood called Diamond Heights west of downtown. Here's a link. You'll note in the description that there are "Twin Peaks" in the area so you're not at all wrong. Seems you did some serious rambling when you visited San Francisco! If you were here today you would definitely have gotten wet. We had alternating periods of sun and rain with dark clouds spreading across the sky. Of course, anyone living in Ireland knows how to cope with rain so likely it would be no problem for you Peter... ;-)