One of Australia’s most recognizable buildings has a handwritten note from Queen Elizabeth II addressed to the residents of Sydney, but it won’t be discovered for another 63 years. A time capsule containing a letter from Her Majesty and strict instructions not to be opened before 2085 is kept in the renowned Queen Victoria Building in Sydney’s central business district. After a comprehensive building restoration work in November 1986, the Queen had written the letter, with strict instructions to only open it in 2085.

Only Her Majesty’s orders are apparent on the letter, which is framed and housed in a glass case in the restricted dome region of the top of the QVB. For nearly 36 years, the sealed letter has been enclosed in the Queen Victoria Building’s vault, which was inaugurated in 1898 to celebrate the diamond jubilee of Queen Victoria.

The “Right and Honourable Lord Mayor of Sydney, Australia” is to whom the letter is addressed, reports Daily Mail. “Greetings. On a suitable day to be selected by you in the year 2085 A.D. would you please open this envelope and convey to the citizens of SYDNEY my message to them,” reads the letter reads, signed by the late Queen. Even the monarch’s personal staff is not aware of what the cryptic letter’s contents are, as they have been kept confidential. Only the Queen’s instructions for when to unveil remain in the public knowledge.

Over the course of the Queen Victoria Building’s history, numerous council studies for remodeling have been done, including one in 1959 when the structure was almost razed for civic space and parking. The building was later refurbished in 1984 by a Malaysian company with a 99-year lease, who based their redesign on photos they could locate of the QVB at the time of its construction.

The British monarch still serves as Australia’s head of state today with King Charles III now head of state after his mother Queen Elizabeth II’s passing. The Queen, who served as a constitutional monarch, did not participate in the day-to-day operations of the Australian Government. However, she did perform significant ceremonial and symbolic duties.

The late Her Majesty Elizabeth II made 16 trips to Australia, the first of which took place in 1954, barely two years after she assumed the throne. More than half of Sydney’s population, or at least one million people, gathered in the city in 1954 to see the new Queen and her spouse, Prince Philip, when they visited to begin their royal tour, per Express. As a 27-year-old, Queen Elizabeth was the first reigning monarch to step foot in Australia when she touched down at Sydney Airport.