The Washington Monument. This is another "amateur attempts to work with elements of photography" image-- as a general rule, horizontal lines work best near 1/3s, not near 1/2s. So I tried to set this one up with the obelisk only 1/3 of the way from the left edge of the frame, instead of dead center. (the actual rule has to do with golden rectangles, but 1/3 is easier to remember.) I do think it works a little b etter in this case. I'm never quite sure what to do about the horizon: it's notably lower than the tops of the trees, but the tops of the trees are part of the visual element one might call a horizon.