The Athens metro is very old, only 6 years younger than the London metro. However, it is not as extensive as one would expect since 1869. There are only 3 lines and they all intersect in a quadrilateral: Monastiraki, Syntagma, Attica and Omonia. The most convenient thing for tourists is that the metro goes from the airport to the port of Piraeus, because tourists often skip Athens and go straight to the port. The trip costs 1.4 euros. The ticket is valid for 90 minutes. However, it is more expensive to get from/to the airport. 9 euros. You can save money on a day pass. It is valid for 24 hours and costs only 4.5 euros. At the same time, it operates on all types of municipal transport. The metro in Athens was put in order for the 2004 Olympics, for which Greece will still pay for many decades. The stations are modern and beautiful. During the construction process, many antiquities were found, which were left right in the subway, making a free museum. So antiquity will meet you already in the subway...