Greek National Road 3

Greek National Road 3 (Greek: Εθνική Οδός 3), abbreviated as the EO3, is a national road in Greece. It connects Elefsina near Athens with the border of North Macedonia at Niki, passing through Larissa and Florina. At Niki, it connects with the M5K motorway to Bitola. The section Kozani - Niki is also designated as the A27 motorway, part of which is operational as a 2-lane motorway.

At 493.5 kilometres (306.6 miles), the EO3 is one of the longest national roads in Greece, with the southern half serving as the main route from Larissa to Thessaloniki until July 1963. The A1 motorway now offers a faster connection to Thessaloniki. Most of the EO3, except the southernmost section between Eleusis and Bralos, is part of the E65.