It has been called the Gibraltar of the Americas.

But a newly released federal report suggests the historic Citadelle fortress in Quebec City is badly in need of reinforcement.

A strategic plan, penned by the army, estimated as much as $100 million will be needed over 10 years to refurbish the redoubt, the foundations of which were laid in the 17th century when King Louis XIV still ruled New France.

The federal government was warned in 2003 in an exhaustive study that the Citadelle, the only historic site in Canada still garrisoned by a regular military unit, would need extensive repairs.

The staggering estimate does not include the costs to bring buildings and ramparts up to "code," said the army's 2007 strategic plan, obtained by the Canadian Press under the Access to Information Act.

Land Forces Command "cannot assume this investment alone," said the assessment.

It asks for help from both Public Works Canada and Parks Canada, which also share ownership of the site.

The Citadelle is home of the 2nd Battalion Royal 22nd Regiment – the Van Doos.

The Governor General also maintains an official residence within the confines of the fort atop Cap Diamant, adjoining the Plains of Abraham.

The army "does not have the resource flexibility to upgrade and maintain" the site, said the report.

"Maintenance of a historical site of this magnitude requires significant recurring investment; particularly since work is strictly regulated by the Federal Heritage Building Review Office."

The army put $4 million into sprucing up the fort in advance of this summer's celebrations marking the 400th anniversary of the founding of Quebec City.

There's still no decision about how to proceed, but a spokeswoman said in an e-mail statement that piecemeal renovations aimed at addressing safety concerns have been carried out.

"Work on the Citadelle has been ongoing over the past five years," said Sarah Kavanagh.

"A series of small projects has been completed to resolve immediate concerns, including the complete restoration of the north-east facade of the north rave line of the Citadelle. To resolve all outstanding issues with the structure of the facility, the department is currently examining options for the way forward."

Preserving memory a goal

The fortress is an emotional touchstone for the Van Doos, who've garrisoned the ramparts since 1920 and made visiting the Citadelle a right of passage for all new members of the entire regiment.

The war in Afghanistan makes the ritual even more stirring.

The regimental museum with its flags, 1,000 medals and 15,000 mementoes of wars past and present give the Van Doos a bayonet-sharp sense of history and the sacrifices going on even today.

Among the garrison duties, individual soldiers on guard duty visit the tomb of a former Governor General, Georges Vanier, who once commanded the fortress, to turn the page in memorial book of those members of the regiment killed overseas.

"We have a responsibility to preserve the memory of the people [who] went there, the people who are there today and those who will be there tomorrow," said Maj. Serge Coulombe, the garrison commander.

A fire last spring at the 121-year-old Quebec City armoury, located just outside the Citadelle, heightened concern about preserving the main fortification.

The star-shaped fortifications have been a work in progress.

After Quebec was captured by the British, Royal Engineers went about expanding and building up the defences between 1820 and 1831 under threat of an American invasion.

In the late 1800s, the defensive works fell into disrepair and were saved by Frederick Hamilton-Temple-Blackwood, Governor General between 1872 and 1878.