The rooftop bar of the A for Athens hotel, on Monastiraki Square, gives one of the best face-on views of the Acropolis in the city — particularly at sunset, when the Parthenon catches the last warm light. It is also the most reliable spot to see the citadel after dark, when it is floodlit.
Drinks are not cheap but the view is — there is no cover charge. Aim to arrive an hour before sunset to claim a seat, and stay through golden hour into the evening. The food is reasonable bar fare; better to come for a drink and eat elsewhere.