I got up fairly early and took the metro to the Cité, one of the most interesting-looking metro stations.
I got in line to see Sainte-Chapelle. First there was the line for the bag search, then the line for tickets, then I could walk into the basement, then into the chapel above--an amazing sight, as I remembered from visiting as a kid. Chairs lined the edge of the chapel, so I sat awhile and stared, then tried (and failed) to match up the descriptions of the biblical events with the images on the stained glass, then wandered out onto the balcony and examined some of the stone carving, then went back to sitting and staring for a while more. I knew that a google image search would probably turn up far more spectacular pictures of the Sainte-Chapelle than I'd ever take, so instead I amused myself by taking pictures of other tourists taking pictures.
When I finally left, I checked Notre Dame, but the line to get in was a little long and I was tired of lines, so instead I sat in a park for a while and then caught the metro for Montmartre.
I tried and failed to find Truffaut in the Montmartre Cemetary, then walked up to the Sacré Coeur. The location was more interesting than the church itself.
By then I was pretty hungry. The owner of the bed and breakfast in Ottawa had suggested the cafeteria on the roof of the Printemps department store as a pleasant place to have lunch. He was right.
Finally I went to see "Les Poupées Rousses" in a movie theater on the Champs Élysée. It didn't impress me much, but it was fun to watch anyway. I'm a poor judge, though, since I probably lost a third of the dialog or so.