A 49-year-old Australian woman was raped, punched in the face and robbed in near Rome's central rail station late on Monday after she spent the evening at a nightclub.
The tourist told police she did not recall being raped but this was confirmed by doctors at Rome's San Giovanni hospital who also reported injuries to her face and groin.
The woman remembered being punched in the face and having her mobile phone and wallet stolen, police said.
Police believe the attack took place in the Colle Oppio park close to the Colosseum, which in recent years has become a haunt for migrants, down-and-outs and drug addicts.
The attacker may have been Romanian, according to witnesses who said they saw the woman walking with a man from the main Termini train station along via Merulana towards Colle Oppio late on Tuesday.
Police were viewing footage from security cameras in the area in an attempt to identify the attacker.
The Austrialian is in Italy to travel and learning the language.