So here you are at the Ellipse and you have simply the best picture of the White House(it looks just like it does on the Twenty Dollar bill, but smaller than it does on The West Wing), there’s this three foot tall stone there. What’s the deal? Well, way back in the day, someone decided that there needed to be a central spot, a marker, from which every distance in the United States is measured. So when they say that it’s 3200 miles to San Francisco, they are measuring the distance to THIS spot.