Outside the walls are remains of two monasteries in the form of ruined dagobas.
Don’t spoil your times, there are much larger and more interesting dagobas waiting for you in Anuradhapura.
The ruined city it extends on a large area and probably lots of its remains are in need of excavations, but the interest is concentrated in the citadel which is surrounded by low walls. Inside it you’ll find what remains from the royal palace. The only interesting thing there is a table with Sinhalese inscription recording a visit of a king of Polonnaruwa to watch a dancing.
There are hourly buses on between Kurunegala and Chilaw, but you need to get off as they are passing through Panduwas Nuwara and then walk from the bus stop.
By far the best option is to reach the site with your own means of transportation as we did (on our way from Colombo to Anuradhapura, visiting also Yapahuwa)