Aron Nagy (39) was found unconscious in the gap between the Cock and Bottle pub and Hettich Jewellers at around 1.15 am.
It is believed he had been stamped on and kicked repeatedly in the head by another man, before being found unconscious by passers-by.
His parents, Aron Nagy and Adrianne Heywood, from the UK, have been by his bedside ever since but he has still not recovered from his head injury.
Police are trying to build up a picture of where Mr Nagy had been before the attack and are keen to speak to anyone who may have seen him on Saturday night.
They also want to speak to anyone who may have witnessed the assault, or knows the suspected attacker, who is described as being just over six feet tall with light-coloured hair.
Police would like any landlord or landlady, neighbour or friend who might recognise him to come forward and give information.
It is known that he was born in Bournemouth.
Police urge anyone with information about this assault to come forward and call 612612 or speak to Crimestoppers on 0800 555 111.