A 23-year-old man has been arrested on suspicion of rape after an attack near Brighton Pavilion.
Police said the woman was raped by a man in the grounds on Saturday, June 8, prompting officers to cordon off the area while a forensic investigation took place.
An appeal was put forward by the force and police have since arrested a man on suspicion of rape.
He was detained on Saturday, June 15, to be interviewed by detectives.
Officers said despite help from members of the public, they are still keen to speak to anyone with relevant information concerning the incident.
They are asked to report it online or call 101, quoting Operation Cobalt.