The public transport system in Athens consists of bus, metro, tram and suburban railway [7] services.
The Athens Metro is one of the most modern systems in the world. It has four lines, three of which are distinguished by the colours used in maps and signs (green, blue and red). The green line, which is the oldest and for the most part runs on the ground, connects Piraeus to Kifissia. The other two lines were constructed mainly during the 1990s and the first sections were put to service in 2000. They run entirely underground. The blue line goes from Monastiraki to Doukissis Plakentias and the Eleftherios Venizelos International Airport, and the red line from Aghios Antonios to Aghios Dimitrios. Extensions to both lines are under construction, most notably to Marousi and Old Hellinikon Airport East Terminal (future Metropolitan Park). The fourth line is the Proastiakos (suburban) which runs from the Eleftherios Venizelos International Airport to Athens Central train station. It is managed by three different companies (ISAP line 1), Attiko Metro (lines 2 & 3), Proastiakos (line 4).
The whole Metro system of Athens has currently 91 km. Considering this issue shows how the mass transport system in Athens has improved in the last years, since until 1999 the length of the system was of just 25 km and comprised by one line. It's expected that for the 2008 it will reach 110 km, after the extensions of the first phase of expansion get concluded.
The bus service consists of a network of lines on which normal buses, electric buses, and natural gas buses run (the largest fleet of natural gas run buses in Europe). There are plenty of bus lines serving Athens and the suburbs, and they link the centre of the city with most of the suburbs and neighborhoods.
The tram runs from Syntagma Square to Palaio Faliro and there the line splits in two branches, going to Glyfada and Neo Faliro. Both Syntagma - Palaio Faliro - Neo Faliro and the Glyfada branch opened on 19 July 2004. Further extensions are considered.
There are many taxis in Athens, which can be recognised by the yellow color of the vehicles. They are quite cheap and during rush hours it is considered normal to halt a taxi even when it is in service (although, strictly speaking, this is forbidden); in that case, if the one halting it happens to go to the same direction as the customer and the customer does not mind (although this is never brought up or an issue), he is also allowed in, and each one pays normally as if they were the only customer.
Athens is served by the Eleftherios Venizelos International Airport at Spata, east of the city, about a 45-minute taxi ride from the city centre. There is also an express line connecting the airport to the metro system and 2 express lines connecting the airport to Pireus port and the city centre. Athens is also the hub of the Greek National Railway System, and ferries from Piraeus Port travel to all Greek islands.