Though the symmetry of Notre Dame de Paris stands out from the mere mortal constructs around it, I enjoy playing the game of identifying the breaks in its symmetry. Some of those are small, like the different statues around the building. Others are more significant, like the triangle in place or an arch above the left-most set of doors.
The bridge in the distance is the Pont au Double, and it is one of several that connect the Rive Gauche to Île de la Cité. That central island fascinates me because it is the site of the medieval refounding of the city. The island used to be packed with residences alongside government and religious buildings. Today it is almost entirely dominated by the latter buildings (like Notre Dame on the right), yet I heard that census information still lists a few hundred people living on the island. Where are those last homes hiding?