Thousands of runners are taking part in the Belfast City Marathon on Sunday.
The 26.2 mile-long (42.1 km) race started at the Stormont Estate in the east of the city.
The route takes runners across Belfast, past landmarks including City Hall and Parliament Buildings, before finishing in Ormeau Park.
This year’s race is being broadcast live in full online for the first time by BBC Northern Ireland.
It can be watched on the BBC iPlayer and at the BBC Sport NI website.
Commentary is being provided by athletes Katie Kirk and John Glover, and BBC presenter Mark Simpson.
“Having been a marathon spectator as well as a competitor, I know it can be difficult to take in the whole event as it covers such a large area,” Mr Simpson said.
“Thanks to the cameras at all the key points, viewers will be able to take in the entire Belfast marathon – in real time – for the very first time.”
Jenny Finlay, from Lagan Valley Athletics Club, is running in the adult female relay event.
“The relay event has teams running for charity, groups of friends – for all sorts of reasons,” she said.
“For us it’s about showcasing our club, about putting all our training into practice and seeing what we can do.
“From [when] I was a child, my dad would have been running in the marathons, so I was always brought along to watch.
“It’s a great event for the city, bringing all parts of the community together.”
The marathon was first held in 1982 and last year marked its 40th anniversary.
It began at Prince of Wales Avenue at the Stormont Estate at 09:00 BST.
Roads on the marathon route started to close wholly or partially from around 06:00 on Sunday and this will continue until 16:00 approximately.
Police have advised road users to expect some disruption and to make use of diversionary routes.
Once all runners have passed points on the race route, the reopening of roads will begin.
A relay and wheelchair race will follow the same route as the marathon, and there is also an eight-mile (12.8km) walk.
This year around 4,500 runners are competing in the marathon and wheelchair race, and 9,000 in the relay.
Last year’s men’s marathon was won by Irish Olympian Paul Pollock, in a time of two hours, 16 minutes and 13 seconds.
The Holywood man had to speed away from the finish line as his wife was expecting the couple’s second child.
North Belfast’s Gladys Ganiel won the women’s race ahead of St Peter’s Lurgan athlete, Gillian McCrory.