More than 120,000 runners have completed the Cardiff Half Marathon since its inception in 2003
Road closures will be in place for much of Sunday for the largest Cardiff Half-Marathon in the event’s history.
A record 27,500 runners are set to take on the 13.1 miles in what has become the UK’s third biggest race.
Castle Street, where the race will start, will be closed from 04:00 BST while other roads will not reopen until 15:15.
At least 50,000 spectators are expected to line the course around the city and are advised to plan their journey.
Cardiff Half Marathon
Many major roads across the city will be closed for parts of Sunday
Runners are being urged to use sustainable travel to reach the start line after research showed 70% went by car last year.
Baggage tents at the Event Village near City Hall will open from 08:30 ahead of the wheelchair race start at 09:55 and the main race five minutes later.
The course is unchanged from 2018 with runners starting in front of Cardiff Castle before heading past Cardiff City Stadium, through Penarth Marina, across the barrage and past the Wales Millennium Centre before circling Roath Park lake and finishing along Edward VII Avenue in the civic centre.
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Residents, runners and spectators are advised to check all road closures as well as changes to Cardiff Bus services.
A park and walk facility has been provided at Cardiff City Stadium on Leckwith Road.
Run 4 Wales
Runners cross from Penarth to Cardiff Bay
A spectator zone will be in place on Corbett Road, close to the finish line where there will be extended tiered standing terraces to allow more people to watch friends or family complete the challenge.
First run in 2003 by just 1,500 athletes, the event has grown into the second biggest half marathon in the UK, behind the Great North Run, as well as hosting elite men’s and women’s races.
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Research by Cardiff University found that runners spent £2.5m in the city at the 2018 event.
Pubs and restaurants have previously seen a “three to fourfold” increase in trade on a typical Sunday in the capital city though other small businesses said they will not open due to a downturn in shoppers and difficulties for staff getting to work.
Live coverage of the Cardiff Half Marathon is on BBC One Wales from 09:30 and BBC Two network at 09:45. Highlights will be on BBC Two Wales at 22:00 and on the BBC iPlayer.