Greek National Road 3 (, abbreviated as
EO3) is a
single carriageway road in
Greece. It connects
Eleusis near
Athens with the border of the
Republic of Macedonia at
Niki. It passes through
Larissa and
Florina. At Niki it connects with the M5K motorway to
Bitola. Greek National Road 3 is one of the longest highways in
Greece and up until the 1960s it served as the main route from Larissa to
Thessaloniki. The new
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.