We went up to the top of the Arc de Triomphe about a half-hour before sunset. From this point, you have a great view of the entire city. We were amazed at the Eiffel Tower, the Sacre-Cuer (sp?), downtown Paris, and the other famous sights. We were even more amazed by the chaotic traffic around the base of the Arc de Triomphe!
Finally, we were able to watch a brilliant sunset from the top. The sun was setting directly behind downtown and made for some spectacular photographs (which I will attach once I have a chance to scan them).
The walk to the top is good exercise to say the least! There's a small museum inside the Arc, and the Tomb of the Unknown Soldier is at the base.