Police are on high alert in Belfast as a massive loyal order parade takes place to mark the centenary of the signing of the pro-Union Ulster Covenant.
The security operation focuses on potential flashpoints on the route, with the area around St Patrick's Catholic church in the north of the city providing most concern.
An estimated 30,000 marchers will take part in the Orange Order event which will see a huge cultural festival staged in the grounds of the Northern Ireland Assembly at Stormont in east Belfast, held to commemorate the 1912 proclamation against plans for Home Rule in Ireland.
Sections of the participants' journeys to and from the main meeting point at Stormont will be monitored by police.
The Parades Commission, which rules on controversial marches, has placed restrictions on both marchers and demonstrators on the part of the parade that passes St Patrick's.
The place of worship has been the scene of disorder at points during the summer after a band was accused of playing sectarian music outside it on July 12.
The 2,000 marchers anticipated to pass the church have been ordered to play only sacred music while passing the venue.
The Orange Order offered to play hymns as members passed the church but a residents' group from the surrounding area requested that no music be played.
A legal attempt at Belfast High Court by a resident to overturn the commission's ruling failed.