The queuing system is very clever, you kind of loop round a raised platform so that your view is lovely and changes all the time! The outside decoration is enough to keep you going...all carved and super-ornate...beautiful! Once inside, the windows in particular are a real treat, the bells were also on display during our visit, and it was very interesting to learn more about them, I was struck by how tall the building is inside, wondrous! We paid to visit the small treasury, which has relics dripping in gold and precious stones...some serious religious bling is kept here! We didn't have time to queue for the viewing platform near the top of the tower, but I bet it would have been worth planning into our itinerary in hindsight. The gift shop was a little disappointing, but did have some lovely beaded decorations for our Christmas tree as a memento of our very pleasant visit. Later in the evening when it was dark, we came back and sat of the raised platform to take in the cathedral at night. I would completely recommend doing this, the lighting is very dramatic and the place takes on a new air of quiet majesty...you can even catch the Eiffel tower all lit up in the background, and a nighttime walk along the river stopping by the little bars is very romantic!