Round Top is a remnant of a 10 million year old volcano, tipped over by tectonic activity. It's pretty high at 1,763 feet. Unfortunately the peak is privately owned so you can't go right to the top but there is a 2.5 mile loop around the peak. You get views out to Mount Tam, Mount Diablo and even the Sierras and an occasional glimpse of the bay. The drive up is also spectacular.