In Redwood City, there’s a round, open-air rotunda that looks like it was plucked right out of ancient Rome. It has stone columns, an ornate dome and even a reflecting pool. It’s called the Pulgas Water Temple, and there’s another one just like it in Sunol, about 40 miles away. … The story of these temples begins back in the 1770s. When the Spaniards chose the location for what’s now San Francisco, it was for strategic reasons. It was the perfect point from which to control the entrance to the bay. … If you follow the water system upstream into the Sierra Nevada, you come to its beginning — the Hetch Hetchy Valley. It was home to Native Americans for thousands of years before Europeans arrived in California. Now it’s underwater, flooded by the O’Shaughnessy Dam. Miners that flooded into California looking for gold made their way into the Sierra Nevada, displacing or killing the Native Americans living there.