Police are seeking witnesses to a city centre assault in the early hours of this morning which left a man with significant head injuries.
South Wales Police said officers found a 23-year-old man unconscious outside the Welsh Craft Shop, opposite Cardiff Castle, at around 2.10am this morning.
The man had significant head injuries and was taken to the University Hospital of Wales.
Another 23-year-old man has been arrested on suspicion of assault and is helping officers with their enquiries, but police are appealing for anyone who witnessed events leading up the assault victim being found to contact them.
A spokeswoman for the force said it was possible people might have seen a group of men in their 20s appearing have a play fight in the area.
Anyone with information should contact Cardiff CID on 02920 527 420 or Crimestoppers anonymously on 0800 555 111.