Before booking your Greece and Europe tour, make sure you have a valid passport and research visa requirements. If your passport is about to expire, you may be denied entry to Greece.
As far as visa requirements go, you may need a visa if you’re not from a Schengen country. You may be able to visit Greece for a period of time without a visa if you’re a US citizen. Take a moment to check the latest visa requirements from an official source or the Greek embassy in your country.