Just off the road leading from Kasteli to Ano Vianos you get the opportunity to make a little detour after the village of Panagia. The sign points into the direction of excavations in the traditional village of Afrati (3 km). As I understood there were the remains of an important, ancient city in the area. We took that detour and got lost. The road ended in a small dirt road barely wide enough for our car, only to find out from the local people that in order to see the sight we had to still walk for an hour or more in order to get there (one of the inhabitants had drawn a map to explain where it was).
The people in the village were very friendly though and the whole place is very authentic. Worth to take a look at just for that. We were invited in for food and wine, which was for us a more rewarding experience than the old stones probably would have been.