A man has been charged with trespassing within the grounds of Windsor Castle, the Crown Prosecution Service (CPS) said.
Robert Pennefather is accused of entering the grounds of the Royal residence in Berkshire in the early hours of November 6 last year.
The castle - the largest and oldest occupied castle in the world - is deemed a designated site.
Trespassing on such a site is considered an offence under the Serious Organised Crime and Police Act 2005, the CPS said.
The Queen was not in residence at the time of the incident.
Zoe Martin, for the CPS, said that Pennefather has been bailed to appear at Westminster Magistrates' Court on March 23.
“I have today authorised the police to charge Robert Pennefather with an offence of trespassing on a designated site after he was found within the grounds of Windsor Castle in the early hours of 6 November 2011," she said.
A Metropolitan Police spokesman said Pennefather, 32, of County Tipperary, Ireland, is on bail.
He said: "Robert James Pennefather, 32, of Co Tipperary, Ireland, will appear on bail at Westminster Magistrates' Court on Friday March 23 charged with trespassing on a protected site contrary to Section 128 of the Serious and Organised Crime and Police Act 2005."