It is definively either Neptune or Poseidon, because of the staf.
I've looked in Italy, the Trevi foundain would have been a match except for the broken staf.
But, I'm not sure this comes from a fountain.
The status doesn't look too damaged by pollution, not much pitting, so its probably not an original, especially if its in Athens.
The beard and hair style is not greek, at least not classical greek, so this is a more modern rendition either Roman, or even neo-classic (if that's the case, it could be anywhere). Maybe the Italian parliement ? in Rome.