
Vatadages were ancient structures built around small stupas for their protection. Only ten such vatadages now remain in Sri Lanka. Medirigiriya Vatadage is one of the better preserved and dates to the late 7th century.
The vatadage is constructed on a high circular platform and accessible via a flight of steps. Its three rings of octagonal columns have carved capitals that once supported what may have been a wooden roof. The remains of a circular wall surround the two inner rings of 16 and 20 columns and around them is a balustrade with the outer ring of 32 columns.
Four entrances lead to the stupa in the center. Around the stupa there are four meditating Buddhas. They face outwards and are all similar in appearance, seated on square Sumeru thrones in half lotus position with hands in the dhyana (meditation) mudra. Their features are now worn and the line where their monastic robes cross their bodies is almost indistinct.
For more details, go to the Encyclopedia of Buddhist Arts: Architecture M-S, page 726.