Remaining parts have either fallen through, as no construction works are currently being undertaken and no further announcements have been delivered by the government.

The EO3 is officially defined as a north-south route through central Greece, running between Elefsina to the south and the Greece–North Macedonia border to the north at Niki:[1] however, the EO3 is split into two parts, because the A27 motorway replaced a short segment of the former near Mavrodendri.

[1] The exact alignment of the EO3 between Mavrodendri and Filotas [el] also varies due to lignite mining in the area.

The EO3 forms part of the European route E962 from Elefsina to Thebes, and the E65 from Lamia to Kozani as well as the short segment from the northern end of the A27 motorway to the Greece–North Macedonia border.

[3] Ministerial Decision G25871 of 9 July 1963 created the current EO3 from all or part of the following short-lived national roads (listed from south to north), which existed by royal decree from 1955 to 1963:[4] Until 1975, the EO3 formed part of the old European route E92 from Lamia to Kozani, the old E90 from Kozani to Vevi, and the old E20 from Vevi to Agios Athanasios.