Agios Petros is a small chapel build on top of a rock hill worth visiting. The place is rather isolated but very beautiful with swifts and swallows flying around the hill-top.
I had seen photos of the chapel but without any clue about its location other than an idea about a possible site between Marathokampos and the cave og Pythagorion. By scanning the area on Google Maps I finally found it here.
We took the unpaved road from Marathokampos to the Pythagorions cave, left the car in the road side and walked the last 2 km.
After visiting Agios Petros it is obvious to continue further and visit the cave where Pythagorion is supposed to have lived.