Kostas' place is a really well located flat, with everything you'll need for a short stay in Athens. We've stayed there for 3 nights with our parents and the space was a bit crowded for 4 of us but if there are 2 or even 3 of you it would be ideal. Walking distance to all main attractions e.g. Acropolis or Zeus Temple. Shop and cafes nearby, nothing fancy but a bit cheaper than in the touristic places. First floor flat means you don't have to walk too many stares when coming back after a full day of climbing hills)