Running in Paris. Any suggestions?

I will be in late mid Decemeber in Paris and I would like to develop few running path.
I will be in Montmartre and I'm interested in two possible routes:

• a small one, near Montmartre, around 10/12 km at max
• a large one, possibily in the center of Paris. This could be even 30km.maybe starting from Montmartre and back.

Does anyone could suggest interesting running paths in Paris?

Thanks in advance!