To get around Athens, travelers can choose from taxis, buses, metro, or trams. A 24-hour ticket for all modes of transport costs €5 while a single bus/metro/tram ticket costs €1.50. Taxis are also readily available and charge by the meter, with an estimated cost of €15-25 from the airport to the city center.
If you have more time, consider visiting the Temple of Hephaestus and the Panathenaic Stadium. If you have less time, skip the Monastiraki Flea Market and the Temple of Olympian Zeus. Additionally, be sure to wear comfortable shoes as there is a lot of walking involved in visiting these historical sites.