Most of the 8th-century Ratnaprasada or 'Gem Palace' lies in ruins today, though it was originally five stories high with a graceful, tiered roof. At its entrance, however, you'll find a beautifully carved mura gala (guardstone), which depicts the Cobra King holding a vase with a flowering branch, with a dwarf attendant at his feet and his head framed by a cobra hood.

In the 8th century a new order of tapovana (ascetic) monks settled in the fringes of the city, among the lowest castes, the rubbish dumps and the burial places. These monasteries were large but unadorned structures; ornamentation was saved for toilets, now displayed at the Archaeological Museum. The monks of Ratnaprasada monastery gave sanctuary to people in trouble with the authorities, and this led to a major conflict with the king. When court officials at odds with the king took sanctuary in the Ratnaprasada, the king sent his supporters to capture and execute them. The monks, disgusted at this invasion of a sacred place, departed en masse. The general populace, equally disgusted, besieged the Ratnaprasada, captured and executed the king’s supporters and forced the king to apologise to the departed monks in order to bring the monks back to the city and restore peace.

To the south of the Ratnaprasada is the Lankarama, a 1st-century-BC vatadage.