Kent Police and the South East Coast Ambulance Service were called to Priory Road at 6am on Friday 25 March 2022 after a man was found with a head injury.
The man, who is in his 20s, was taken to a local hospital, where he remains receiving treatment.
Officers are investigating how he came by the injury and are appealing to anyone with any information to come forward.
In particular, officers would like to speak to a woman who handed in a wallet at Dover Police Station at around 9am the same day.
Witnesses are urged to call 101, quoting reference 25-0142.
