Parades are taking place across Northern Ireland
to mark the culmination of the province’s annual marching season.
But rioting last night means events will be watched closely for further signs of unrest.
Crowds in nationalist areas threw petrol bombs and other missiles which the authorities say were aimed at police.
27 officers were injured in the rioting, three of whom were shot but not seriously injured.
Local media said the violence began when police tried to seperate people gathering in a nationalist area from those attending ceremonial bonfires nearby.