Konstantinos' space is perfectly located for exploring Athens. We stayed for 6 days and had no trouble getting to all of the historical sites and the tavernas on the same street had the best food we had during our time in Greece.
The apartment is set up thoughtfully, so you can get a quiet night of rest in the bedroom or sit on the balcony and listen to the city.
We would absolutely recommend staying here if you want to be in the heart of the city.