European route E66 is a part of the International E-road network.

This Class A intermediate west-east route runs 651 kilometres (405 mi) from Franzensfeste in Italy to Székesfehérvár in Hungary, connecting the Alps with the Pannonian Plain.

The E 66 routes through three European countries: Hungary requested in October 2011 that E66 should be extended from Székesfehérvár via Dunaújváros - Kecskemét to Szolnok.

[1] This has not taken effect, so in 2019 Hungary requested the same extension Székesfehérvár – Szolnok again.

[2]