I have a 4-hour, 20-minute layover at Warsaw Chopin Airport. Should I wait this out at the airport, or would it be feasible and worthwhile for me to try to see something of the city? If the latter, do you have any suggestions for transportation and destination? This would be on a Sunday between 1 p.m. and 5:20 p.m.
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First, I suggest getting a taxi over a bus, you'll have much more time with a taxi. Head to Warsaw Old Town, walk around and explore, you won't be bored there's plenty to do.