I think everyone knows Eiffel Tower.  It is the tallest building in Paris, it is a global cultural icon of France, and it is the most paid visited monument in the world.  It symbolizes freedom and beauty and everything that is French and Parisian.  Today, surrounded by a fence, and an army of security guards waving metal detectors like fly swatters the experience is somewhat diminished.  It is still beautiful and captivating but not like it used to be.