The 43rd Belfast City Marathon is due to kick off later with runners aiming to complete the 26.2-mile course.
The race will start at Stormont at 9:00 BST and finish in Ormeau Park.
Record numbers are due to take part this year – organisers say 6,500 full marathon runners have signed up, 2,750 relay teams (which have between two and five people in them) and there are 1200 walkers.
There will be numerous roads closed and changes to public transport for much of Sunday as it gets underway.
The course takes in all parts of the city, starting off in Stormont in east Belfast and heads south, taking in the Boucher Road, west, taking in the Falls Road, then north, past the Waterworks, as well as through the city centre, before ending in Ormeau Park.
The Team Relay consists of five legs, of varying distance, with changeover points across the route.
There are some slight changes to the route in 2025 compared to previous years.
Last year, Kenyans Mathew Kiplimo Kembo and Beatrice Jepkemei won the men’s and women’s races respectively.
Chairman John Allen said the organisation was “delighted” to welcome participants of all ages, abilities, and backgrounds.
What roads are closed?
For a full comprehensive list of what roads are closed and when they reopen you can click here.
There will be some disruption for the duration of the marathon, with the Upper Newtownards Road closing at the Comber Road junction from about 06:00 until 11:00.
Roads along the route will open and close on a staggered basis as runners pass.
Organisers say roads will reopen as quickly as possible one runners pass key routes.
The last road to reopen will be the Ravenhill Road from the Rosetta Roundabout to the Ormeau Embankment (where local access is being maintained) which closes at 09:00 and does not reopen until 16:00.
Marathon organisers have asked that motorists please follow the traffic diversion signs and take direction from stewards.
“These traffic management measures are set up to prioritise safety for participants and road users,” said Chairman John Allen.
To help people going to the marathon there will be special early morning trains from Londonderry, Larne, Bangor, and Newry to Belfast Lanyon Place.
For a list of all special departure times click here.
Public transport around the city will be affected due to several road closures.
Ulsterbus, Metro and Glider bus services within Belfast will be subject to delay or disruption.
