Running in Paris?

It's easy to get lost in Paris, so be aware that roads don't run parallel to one another so you can really get lost in a hurry.

I would also run early in the morning (very early) to avoid the pollution and congestion.

Plan your route, bring a metro ticket just in case.

Although I wasn't a runner when I studied in Paris, I would think Jardin du Luxembourg (Luxembourg Gardens) would provide good running, with gravel paths and beautiful scenery.  It's located in the 6th Arrondissement, off of Blvd. St. Michael.  There is a Luxembourg metro stop that would let you out just outside of the park.  I used to walk through the Jardin daily on my way to and from class, and was never concerned for my safety.

I will have to second the running along the seine quays suggestion. When i visit my sister, who used to live in the St. Paul area in the marais arrondisement, i would start there and run to and along the river crossing over to isle d' la cite and basically taking a great scenic tour. I recall running all the way down the river to the Tower and back with no problem. It is definately really pretty, especially this time of year.

-andrew