Highway 1 or A01, formally called the Ring Road (Pashto: د افغانستان حلقوي سړک; Dari: شاهراه حلقوی افغانستان), is an ancient 2,200 kilometre two-lane road network circulating inside Afghanistan, connecting the following major cities (clockwise): Kabul, Maidan Shar, Ghazni, Kandahar, Delaram, Herat, Sheberghan, Mazari Sharif, and Puli Khumri. Originally built and renovated by the Mauryan Empire, it was a part of the Grand Trunk Road project and well documented by Greek and Buddhist sources in the 4th century BCE. It was renovated many times, by Sher Shah Suri, Mughals and the British Empire. It has extensions that also connect Jalalabad, Bamyan, Khost, Lashkargah, Zaranj (Route 66), Islam Qala, and Kunduz. It is part of AH1, the longest route of the Asian Highway Network.
Part of Highway 1 has been refurbished since late 2003, particularly the Kabul–Kandahar Highway, with funds provided by the United States, Saudi Arabia and others. Most work on that stretch was done by Turkish, Indian and local companies. Japanese companies were also involved near the southern Afghan province of Kandahar. In the west, Iran participated in the two-lane road construction between Islam Qala and the western Afghan city of Herat. Pakistan rebuilt the Jalalabad–Kabul Road.