These are spread across seven states in India: Bihar, Jammu and Kashmir, Maharashtra, Puducherry, Punjab, Tamil Nadu and Uttar Pradesh.
The brick stupa was erected to commemorate the event of offering honey to Buddha by the chief monkey.
The bricks lined seven-tiered tank which is approximately 65 X 35 meters in dimension having two bathing ghats on southern and western wings.
In the third phase, it was converted to a monastery in post Gupta times by providing a number of partition walls.
The other monastery which looks like a swastika has 12 rooms, 3 on each arm attached to a common veranda which is around an open central courtyard.
Antiquities like beads of semi-precious stones, terracotta figurines, seals and sealings, bricks embedded with semi-precious stones, inscribed polished and a unique terracotta figure of crowded monkey found during excavations of the sites are kept on display for visitors in local site museum run by ASI.
Originally it was mud stupa, smaller in dimension, erected by Lichhavis over their share of relic of Buddha in circa 5th century B.C.
The library building was air-conditioned by cooled water from the adjoining reservoir through a range of vents in the black well.