Everything was exellent!
First of all - it is an amazing place, new and convenient appartment in a 5 minutes walk from Monastiraki metro station, i.e. within 1 hours from the airport via metro! The penthause has an astonishing view on the Acropolis, Agora, and the Athens - 360-degree! Terrace with a hammock! Even bathroom has an unforgetable view! Good air conditioning, kitchenware and elevator (!) in the building are also included.
At second - the location is also superb for exploration of the historical sites in the city center: 3 minutes on foot to Agora historical site and museum, flea and central markets are 5-10 minutes on foot! Prime location!
At third, many thanks to the host, Fotis and his colleague John, who provided us with some refreshments and breakfast food (we arrived late), recommended nearby bakery and a good restaurant for dinner. They were welcome and friendly!