The route spanning the Grand Trunk (GT) road existed during the Maurya Empire, extending from the mouth of the Ganges to the north-western frontier of the Empire. The predecessor of the modern road was rebuilt by Sher Shah Suri, who renovated and extended the ancient Mauryan route in the 16th century. The road was considerably upgraded in the British period between 1833 and 1860.
Research indicates that during the time of the Maurya Empire in the 3rd century BC, overland trade between India and several parts of western Asia and the Hellenistic world went through the cities of the north-west, primarily Takshashila (Taxila in present-day Pakistan, see inset in map). Takshashila was well connected by roads with other parts of the Maurya empire. The Mauryas had built a highway from Takshashila to Pataliputra (present-day Patna in India). Chandragupta Maurya had a whole army of officials overseeing the maintenance of this road as told by the Greek diplomat Megasthenes who spent fifteen years at the Mauryan court. Constructed in eight stages, this road is said to have connected the cities of Purushapura, Takshashila, Hastinapura, Kanyakubja, Prayag, Pataliputra and Tamralipta, which had essentially been around 2600 kilometers as per current estimates.
^Chaudhry, Amrita (27 May 2012). "Cracks on a historical highway". The Indian Express. Archived from the original on 22 May 2013.quote: What Chandragupta had begun, his grandson Ashoka perfected. Trees were planted, ... Serais built. p.2
^David Arnold (historian); Science, technology, and medicine in colonial India (New Cambr hist India v.III.5) Cambridge University Press, 2000, 234 pages p.106
^A description of the road by Kipling, found both in his letters and in the novel "Kim". He writes: "Look! Brahmins and chumars, bankers and tinkers, barbers and bunnias, pilgrims -and potters - all the world going and coming. It is to me as a river from which I am withdrawn like a log after a flood. And truly the Grand Trunk Road is a wonderful spectacle. It runs straight, bearing without crowding India's traffic for fifteen hundred miles - such a river of life as nowhere else exists in the world."
Usha Masson Luther; Moonis Raza (1990). Historical routes of north west Indian Subcontinent, Lahore to Delhi, 1550s-1850s A.D. Sagar Publications.