The 14thC Statue of the Virgin and Child, Notre-Dame de Paris.
The south side Rose Window showing Christ and the Apostles. If you're really interested, bring binoculars!
East side stained glass.
Gargoyles watching the apostles on Notre Dame Cathedral roof, though one of the figures is apparently the sculptor.
Terrific city views from the roof parapet even if tourists are caged in by wire, this one looking west to La Défense, with Sainte Chapelle's spire slightly right of centre. Another rooftop shot. Next, Sacré Coeur and Montmartre.
Official Notre Dame site