A time capsule hidden inside the pedestal of a statue of King Willem II in the Binnenhof parliamentary complex for almost a century has been opened by The Hague mayor Jan van Zanen.

The lead box, found during the renovation work done to the complex, was placed into the pedestal on January 29, 1925. It was discovered three weeks ago but officials waited to present its contents to the public until the 29th to make up the not quite round number of 99 years.

The statue of Willem II mounted on a horse, which was placed on the Binnenhof in 1924, had been removed in November but the pedestal remained. When it too had to go, the box came to light.

Van Zanen said the event reminded him of Raiders of the Lost Ark and said the box was “heavy and well-filled” as he opened it to reveal the contents.

Among the papers found is a letter addressed to the finder of the box, written in 1924 by the then cabinet chief, a handwritten document describing the statue’s unveiling by then queen Wilhelmina in the same year and a book commemorating the battle of Waterloo, in which Willem II took part.

“The document shows who were present at the unveiling. It gives an impression of an era that was becoming more modern, because, apart from a lot of army brass, the first Dutch female journalist Emilie Belinfante was also present,” architectural historian Patrick Bosman told Nu.nl.

The book about the Battle of Waterloo, which took place in 1815, was in a pristine, uncut condition, prompting Van Zanen to joke that “someone must have been sent to the bookshop around the corner for it at the last moment”.

The box also contained an ode to the king, written by a schoolmaster. All the documents were in excellent condition, Bosman said.

The box and its contents will be exhibited at the Binnenhof renovation information centre from January 31 for a week. It will then be kept in the archives and returned to the pedestal at the end of 2028, when the renovation, which began in 2021 and was initially thought to take just 5 years, will be finished.

The Hague local council will add some new items to the box but has not yet decided what.