Nine hundred years of history are about to be entrusted to the removal men as they are packaged up and ferried to Belfast’s docks.

Archivists, conservators and curatorials at the Public Records Office of Northern Ireland (PRONI) are bringing in the bubble wrap as they transfer some 3 million documents from their Balmoral Avenue headquarters to their new premises in the Titanic Quarter.

If all the boxes in the archive were laid down end to end, they would stretch 40km — from Belfast to beyond Ballymena.

Among the treasures held by PRONI are a Papal Bull dating from 1219 — the oldest document in the collection. Other fascinating glimpses into the history of Ulster include a photograph of General Eisenhower on the steps of Stormont in 1945, images of the Armagh rail crash in 1889, at the time the worst in Europe with the loss of 78 lives, and photographs of Belfast Telegraph printers hard at work in 1898.

But time has taken its toll and the Balmoral building is no longer fit for purpose. The sliding book bays packed into a series of humidity controlled rooms deep in the bowels of the building regularly jam, holding up retrieval of documents, and the reading room was recently forced to close for a couple of days when a pipe sprang a leak.

Although the Titanic Quarter project will cost £29.5m, it would be even more expensive to carry out the required upgrades, and it would still be too small for the volume of records it holds.

On September 3 the office will close and it will take about eight months for staff to complete the move.

In the meantime, PRONI is increasing its online offering and will open a self-service microfilm facility at Cregagh library.

Transferring the documents will be a painstaking process — so many of them are both delicate and irreplaceable.

Laurence Stanford, deputy project sponsor of the Titanic Quarter project, said: “These archives are unique. If a document is lost or damaged you can’t replace it. It’s not like a library book which can be bought back in — once it’s gone, it’s gone.”

The archives are already proving to be a major tourist draw and once they move to the new building at Titanic Quarter, that trend can only continue.

Last year, nearly 18,000 people visited the Balmoral premises and PRONI has been the mother-lode for anyone intent on tracing their roots in Northern Ireland.

Ten things you didn’t know were buried deep in the archives

1 Contingency plans for distributing and baking bread in the aftermath of an atomic bomb attack on Northern Ireland in 1953.

2 An account of an unsuccessful attempt at witchcraft in Carnmoney in 1807, which resulted in three deaths due to sulphur poisoning.

3 A scorecard featuring WG Grace in 1875 between North Cricket Club and a United South of England side.

4 Correspondence in the Londonderry Papers with WB Yeats, GB Shaw, AE Russell, Thomas Hardy, Sean O'Casey and Oliver Gogarty.

5 Letter from Napoleon to the King of Prussia, April 1807.

6 Missionary records of the Qua Iboe Mission in Nigeria, 1887-1963.

7 Poster for Ginnett's circus and hippodrome, Glengall Place, Belfast, 1885-1886.

8 Recipe for Asthma cure: “One ounce of Black Night Shade roots, dried and pounded, mixed with one pound of tobacco and smoked in a pipe when fit of asthma starts”.

9 Photograph of the first car in Markethill.

10 Papal Bull dating back to June 12 1219 — the oldest item in the PRONI collection. It’s part of the papers from the Abercorn estate and concerns the granting of lands to an abbey.