The man was rushed to the Great Western Hospital in Swindon with life-threatening injuries after being found next to a car in Carneigie Mews.
Police officers are now investigating the circumstances which led to the man being found this morning with head injuries.
They were called by the ambulance service at 7am to what was initially believed to be a medical incident after the man was found next to a car in Carnegie Mews.
He has since been taken to the Great Western Hospital where he is in a life-threatening condition.
Det Sgt David Hambly said: “We are currently treating this as an unexplained incident and would like to hear from anyone who may have seen the man in the area or anything suspicious between 3am and 5am.
“While there is nothing to suggest a crime has taken place, we would like to bottom out the circumstances which resulted in this man being found in this condition.
“If anyone in the local vicinity has any CCTV footage that could assist with our enquiries, please call 101 and quote log 35 of today’s date.
“We understand this had an impact on several local businesses and would like to thank them for their cooperation.”