We are arriving at 8 am at PIreaus via cruise ship and will have the day in Athens, then catch a late pm flight out.
It is reasonable to plan a day at the Acropolis and then perhaps the National Museum before catching a 5:30 flight?
I'm thinking the metro, but not sure about carrying our backpacks all day.
"not sure about carrying our backpacks all day"............
Not a problem. Take the Green Line Train from Piraeus into Central Athens to the Monastiraki Station. Monastiraki is very close to the Acropolis, an easy walk. On the corner of Monastiraki Square is "Athens Lockers / Left Luggage - Monastiraki". Park your backpacks there, visit the Acropolis and the National Museum then return to Monastiraki Square to retrieve your backpacks before catching the Blue Line Metro from the Monastiraki Station out to the Airport.
Thanks! this is exactly the info I needed. We have a plan!