Half of Fuencarral
I'm going to recomend you the one of the last half i did.
This is Fuencarral Half, downhill form 1-7km then flat 7-12 after that all uphill. It's hard but also fantastic when you reduce your personal time as i did.
GPS export File : Fuencarral Half

I'll see you at Madrid Marathon, in less than tree weeks.
Enjoy !!!