Agam Kuan (Hindi: अगम कुआं ,"unfathomable well") is an ancient well and archaeological site in Patna, India. It is said to date back to the period of Mauryan emperor, Ashoka (304–232 BCE). Circular in shape, the well is lined with brick in the upper 13 metres (43 ft) and contains wooden rings in the remaining 19 metres (62 ft).