In spite of problems

 A few weeks ago I tried to run along a track I hadn't run on before, from the north end of Jaca, more or less parallel with the main road to France. After a while I crossed a bridge called Puente de las Grajas; rook bridge and followed a paved road back towards Jaca on the other side of the river Aragón. I thought I'd be able to get to the medieval bridge of San Miguel and from there go up to Jaca, but I found this: 

and I understood I couldn't carry on. At this point, there's a pipe coming down from the top of the mountain which reaches a kind of golf-ball structure. I think there's a hydro-electric turbine in it. 

Here's the pipe in the distance

And the golf ball structure

Well, that day I turned round and went back the way I'd come, there was nothing else I could do and noone to ask.

Yesterday I tried the other way, this time walking, not running. I started off at what they call the Rompeolas, the breakwater, because it looks as if it belongs on the seafront. I went down to St Michael's bridge
 

(sorry, I didn't take my own photo)

On the other side I turned right and walked towards Asieso, with the river Aragón on my right. Reaching the turning for the tiny village of Asieso I turned and immediately found a sign for the Puente de las Grajas.

This was quite an easy footpath until I found my way blocked by red and white tape and a car.

I couldn't think how it had got there, but it must have been some kind of off-roading that went wrong. 

I really didn't want to turn back, so I ducked under the tape and carried on following the footpath, with its little wooden footbridges across the streams going down into the Aragón river. 

By this time I was almost at the golf ball, emerging on the other side of where it said no entry.

I came out from the right-hand side, not the left, where the no entry sign is.

Well, from there it was easy enough. I went along the paved road to the Puente de las Grajas and crossed the river again, then turned right along the footpath leading back to Jaca, past the little chapel of San Cristóbal, where I found another blockage of the path: 

A fallen tree, making difficulties for cyclists and horses

but no trouble for lone walkers.
I'm glad I managed to find the way!