I was in Greece a couple summers ago, and stayed there for 2 weeks. There's an electric train/trolley system that runs through the city, which I mostly used to get around to look for skate spots. I had no idea where anything was, but I found some pretty decent spots.
This one is right downtown across from the Parliament building, if I remember correctly.
I stayed at a hotel across from the beach. Drivers are crazy there.
There is a particularly nice spot I skated that had white banks of all shapes and sizes in addition to gaps and benches. I think it was in the shopping district, even though I could not give you any legit directions. Surprisingly I have not seen that spot in any videos.
The last day I was there I met some Greek skaters at a loading dock sidewalk gap that Dylan Reider nollie flips in an Analog tour video. They were nice dudes, and appeared to be pretty good at skateboarding.