I have spent a great time at Kalliopi, she is a very nice and easy-going person and a very generous host, I can just recommend her place to anyone. Her flat is in the centre but in a calm neighbourhood just 10 mins walk from Acropoli metro station, convinient both day and night. The flat is supernice and newly refurbished (or seem like it is!), with a great balcony, so it is a really good starting and finishing point before and after a busy day in Athens. I am coming back soon, so I'm serious! :)