And to give something in return, for Athens I can heartily recommend Taf Coffee [1], and also MOTIV [2] just across the small street, and in Vienna I have a soft spot for CoffeePirates [3]
[1] https://www.google.com/maps/place/Taf+Coffee/@37.9834313,23....
[2] https://www.google.com/maps/place/MOTIV/@37.9835867,23.73117...
[3] https://www.google.com/maps/place/CoffeePirates/@48.2173765,...