The major excavation at Kumhrar site started in 1911-12 when the archaeologist of British Archaeological Survey of India, D B Spooner undertook the excavation work. Funded by Ratan Tata, the excavation carried on till 1914-15. The historical discovery was the finding of a pillared hall, belonging to the Mauryan period. A total of 72 pillars were excavated at that time. Later excavation in 1951-55 under Historian A S Altekar and Vijayakant Mishra yielded 8 more pillars, thus totaling 80 pillar, after which the excavated hall came to be known as 80-Pillared-Hall. The later excavation also yielded 4-additional pillar belonging to the entrance.
Though only a part of the original pillars were found, including one big pillar which is at display in Kumhrar Park, yet it reflected a highly symmetrical patterned hall. The pillars were arranged in 10-rows that stretched from east to west and 8-rows that stretched from north to south. The entrance was located in the south. Each pillar measured 9.75 meter (~ 32 feet) in height, with 2.74 meter (~9 feet) buried in ground, and placed at 4.57 meter (~15 feet) apart from each other. The pillars were fixed in a wooden basement. The hall's floor and roof was made up of wood. There was no indication that the hall was closed by walls on the sides. Probably, it was an open pavilion. The pillars had shining luster and were brought from sandstone quarries of Chunar in Mirzapur district of Uttar Pradesh. Near the entrance, there were 7-platforms made of Sal wood which probably supported a broad wooden staircase of about 30 steps descending down to a canal connected to river Sone. This staircase was used by the distinguished visitors coming to the hall by boat. There is doubt over the purpose of the hall during Mauryan period. However, it is believed that it was the conference hall for the third Buddhist Council that was held in Pataliputra under the patronage of Ashoka in 3rd Century BC.
The excavated hall is not visible as it has been covered with sand to save it from the problem of water logging. The two millennium hall is still buried, though a pillar has been placed at the surface to give a glimpse of the remarkable finesse of the masterpiece. A replica of the hall is placed in museum, situated inside the park. A better option would have been to cover the entire hall area in a hanger way, just the way China's Terracotta Warriors (UNESCO heritage) are covered, and let the sand be uncovered to make the remnants of the hall visible to the public.