Queen Elizabeth II visited Australia in November 1986. On this occasion she wrote a letter to the citizens of Sydney, and the letter was secretly sealed in a vault in the Queen Victoria Building. Best of all, the letter must not be opened for another 63 years.

Therefore, the letter has been in a vault for almost 36 years, and reportedly not even the Queen’s staff know its contents. It is addressed to the Mayor of Sydney, and only the part containing instructions for opening and reading the letter is visible.

“Greeting. On a suitable day of your choosing, in the year of the Lord 2085, I ask you to open this envelope and convey my message to the citizens of Sydney,” the letter reads.