The Sugarhouse Night Club, Sugar House Alley, Lancaster.
Approximately 1400 people were at the club that night for a Freshers' Week party to welcome new students to the university.
The Police have issued an appeal for anybody with any information about this incident to come forward, saying:
"We would like to reassure people that anybody who does come forward with any information will be treated with respect and sensitively as we appreciate this is a very difficult matter.
"We understand people may feel anxious and alarmed at this time, but we would like to reassure students that serious sexual assaults are very rare.
"We would also like to reassure students that there is a full team of detectives working on this case and we are doing all we can to find the person responsible.
"The woman is being supported by specially trained officers and the University at this time and we will continue to offer her support for as long as she needs it.
"Please contact Lancashire Police on 101 and quote log reference number LC-20131002-0663 or call Crimestoppers on 0800 555 111. "
Virtual-Lancaster's guide to rape prevention:
Rape is a serious criminal offence. Don't rape.