Ajatashatru in the context of "Udayin"

Pataliputra (IAST: Pāṭaliputra), adjacent to modern-day Patna, Bihar, was a city in ancient India, originally built by Magadha ruler Ajatashatru in 490 BCE, as a small fort (Pāṭaligrāma) near the Ganges river. Udayin laid the foundation of the city of Pataliputra at the confluence of two rivers, the Son and the Ganges. He shifted his capital from Rajgriha to Pataliputra due to the latter's central location in the empire.

It became the capital of major powers in ancient India, such as the Shishunaga Empire (c. 413–345 BCE), Nanda Empire (c. 460 or 420 – c. 325 BCE), the Maurya Empire (c. 320–180 BCE), the Gupta Empire (c. 320–550 CE), and the Pala Empire (c. 750–1200 CE). During the Maurya period (see below), it became one of the largest cities in the world. As per the Greek diplomat, traveler and historian Megasthenes, during the Mauryan Empire (c. 320–180 BCE) it was among the first cities in the world to have a highly efficient form of local self government.The location of the site was first identified in modern times in 1892 by Laurence Waddell, published as Discovery of the Exact Site of Asoka's Classic Capital. Extensive archaeological excavations have been made in the vicinity of modern Patna. Excavations early in the 20th century around Patna revealed clear evidence of large fortification walls, including reinforcing wooden trusses.