Agam Kuan, considered as Patna's most quaint monument, is famous for its two important relics – both enveloped in the mystery of legends. The first is Agam Kuan (the unfathomable well), the fabled huge well fed with the Ashokan legends. The other is the famous temple of Shitala Devi, the goddess of the smallpox, a associated with lots of miracles.
The site is situated at a short distance south-west of Gulzarbagh Station. Agam Kuan is a huge well, circular in plan, with a diameter extending over 20'2". It is brick-encased in the upper half of its depth. As many as eight arched windows, all at regular intervals, adorn the well just above the ground and form its most distinctive future.
The well is 105' deep, as far has been fathomed and recorded. Upto a depth of 44' from the surface, a finely worked brick-casing is envisaged. The lower half, a further depth of 61' is, however, secured by a series of wooden rings.
The adjacent temple housing the image of Shitala Devi, and the pindas of the 'Saptamatrikas' (the seven mother forms), is widely revered and worshipped not only for containing the small-pox, but for fulfilling all sorts of desires. The site once contained several ancient and medieval sculptures. Of these, at least one was that of the Yaksha of the Mauryan art-affiliation. This is what Cunninghum reported when he visited the site in 1879-80. But we have no idea now of its whereabouts, whatsoever.
Waddell on his exploration of the ruins of Patliputra during 1890s identified Agam Kuan with the legendary hell built by Ashoka for torturing people as cited by the Chinese travellers of the 5th and 7th centuries A.D. Another legend, still very strong, is that Ashoka threw 99 of his elder brothers in this well after killing them, in order to become king. The site also feeds the Jain legends. The most famous of them is about a Jain Monk Sudarshana who, when thrown into the well by an atrocious king Chand, was found floating over its water seated on the lotus.
People, at large, believe the well's water to be endowed with miraculous power, and the well auspicious.
Bihar became the first state in India to have separate web page for every city and village in the state on its website www.brandbihar.com (Now www.brandbharat.com)
See the record in Limca Book of Records 2012 on Page No. 217