A man in his 50s was found with a serious head injury on the university bridge in Lincoln.
Police were called at 11.45pm on Saturday, May 16 to reports a man had been found on the pavement and had been assaulted.
The man was taken to hospital, where he remains with a serious head injury.
A Lincolnshire Police spokesperson said: “We are appealing for anyone who may have seen this man or witnessed what happened to him to contact us.”
Anyone with information should call 101.