Grand Trunk Road

There was trade along parts of the route far earlier, but the road became clearly established during the Maurya Empire, 322 – 185 BCE, when it was known as uttarapatha (road to the north) and ran from the mouth of the Ganges (near what later became known as Calcutta and is now called Kolkata), through the Empire's capital in what is now Patna, then via the then-great trading city Taxila and through Afghanistan, all the way to the Central Asia region of Bactria.
Later Indian rulers, especially the Mughals, did quite a lot of work on upgrading the Calcutta-Kabul part of the road and extended it east into what is now Bangladesh. However, the Kabul-Bactria section was not considered part of their Grand Trunk Road since Afghanistan was outside their influence.
The British also improved the road when they ruled India and, after the British left, the various nations along the route have done so as well.

Some of the main places on the route today, listed east-to-west, are:

In Bangladesh

• Chittagong, a major port and the eastern terminus of the GT Road
• Sonargaon, once a regional capital, near present-day Dhaka

In India

• Howrah, near Kolkata
• Varanasi, a holy city for Hindus
• Allahabad, another major Hindu pilgrimage center
• Kanpur
• Kannauj
• Etah, district
• Aligarh

Agra
Mathura

• Delhi, India's capital
• Kurukshetra, where the Bhagavad Gita was spoken
• Ludhiana, large industrial town
• Amritsar, center of Sikh culture

In Pakistan

• Lahore, lovely Mughal city and centre of Pakistani culture, provincial capital
• Rawalpindi, an older city located next to Pakistan's capital Islamabad
• the fascinating archaeological sites at Taxila
• Peshawar, capital of Khyber Pakhtunkhwa
• the Khyber Pass

In Afghanistan

• Jalalabad
• Kabul, national capital

In Bangladesh

• Sundarbans, a national park along the Bangladesh-India border with extensive mangrove forest and some tigers
• Mosque City of Bagerhat, home to several notable Turkic-Bengali mosques, including the Sixty Dome Mosque

In India

• Sundarbans National Park, the Indian park; the two parks together make up the world heritage site
• Bodhgaya, where the Buddha reached enlightenment, is not far off the GT road
• Delhi has several world heritage sites

In Pakistan

• Lahore — Fort and Shalamar Gardens, Wazir Khan Mosque, Badshahi Mosque, Tombs of Jahangir, Asif Khan and Akbari Sarai
• Hiran Minar and Tank near Sheikhupura
• Rohtas Fort near Jhelum
• Taxila
• Shahbazgarhi near Mardan