Attiki Odos (Greek: Αττική Οδος) is a private-owned superhighway in Greece. The entire stretch is tolled. The future high-speed rail is almost entirely in the median throught the main section. Its numbers are 6 for the main section and 65 for Aigaleo and Ano Liosion Rings. It is the by-pass of Athens
Construction began in 1996. The superhighway was opened along with Eleftherios Venizelos International Airport where it is connected. The freeway ran from the Gerakas Street interchange but it didn't had access to Keratea directly until 2003 or a northbound interchange until 2002 to Athens from Athens. And the western part ran from Greece Interstate 1 and Kifissou Avenue to what is now exit 9.
In May 2001, an interchange 20B (now K2) opened for Koropi North and reads mainly a local road. Construction from Kifissou Avenue to Gerakas continued while the western part becan construction. The Hymettus ring was under construction.
More interchanges were opened later including the Paiania-Spata Road.
In September 2002, the high-speed railway began construction and the central part of the main section began paving.
In early-2003, Attiki Odos was now operated from Kifissou Avenue to Eleftherios Venizelos Airport. The Hymettus Ring was almost paved that time but the tunnels were constructed.
In late-2003, the Hymettus Ring became fully accessible with a toll booth at the northbound lanes near Katechaki Avenue. The superhighway includes tunnels, . Its length is from Katechaki Avenue to east of the main section with a junction to the westbound lanes of the main section in the middle. It runs in the northern part of the Hymettus and became the road that bypasses Mesogeio Avenue and links to Kifissou Avenue and its suburbs and the Airport along with the eastern suburbs from the eastern part of Athens.
In 2004, the western section along with a tunnel opened from the junction with GR-8 to Kifissou Avenue. It has 7 interchanges in total. and runs between the mountain ranges of Aigaleo and Parnitha. The Ano Liosio Ring is still under construction