Rathnaprasada or Gem Palace is the Uposatha garaya (Chapter House) of Abhayagiri viharaya built by king Kavantissa, also known as King Kanitta thissa, during the 192-194 AD. To compete with Lovamahapaya (Brazon Palce).
Even though the present Rathnaprasadaya is in ruins the monolithic pillars, guard stones and remaining structure of the building support the theory of the archaeologists have discovered that the building was originally 7 stories high with tiered roof and front of the building was completed with beautiful guard stones (Mura Gal) and statue of Buddha made of gold.
The carvings exhibit the architectural marvel present at the time, with a mythical dragon, 7 headed cobra and dwarf servants. These guard stones considered the most preserved and most intricate guard stones found from Anuradhapura era, stands proudly to this day.