Asian Highway 1 (AH1) is the longest east-west route of the Asian Highway Network, running 20,557 km (12,774 mi) from Tokyo, Japan via North Korea, South Korea, China, Southeast Asia, Bangladesh, India, Pakistan, and Iran to the border between Turkey and Bulgaria west of Istanbul where it joins end-on with European route E80, running all the way to Lisbon, Portugal.

From Fukuoka, the Japan–Korea Undersea Tunnel has been proposed to provide a fixed crossing.

The section in South Korea mainly follows the Gyeongbu Expressway.

The Highway Boundary of South and North Korea.

The E80 continues in the E-road network from the border station at Gürbulak in Turkey to Istanbul followed by E80 highways to Kapitan Andreevo/Kapıkule, Sofia, Niš, Pristina, Dubrovnik, Pescara, Rome, Genoa, Nice, Toulouse, Burgos, Valladolid, Salamanca and finally Lisbon on the Atlantic Ocean.