The Ordnance Building in Saint John, once deemed surplus and left unwanted, was declared a National Historic Site on Tuesday.

The former British military depot for weapons and ammunition in the city’s south end was restored after being acquired by John Irving’s property development company.

“To be honest, we came across it because there was an advertisement in the newspaper saying the federal government had declared this property surplus and we said we'd better check this out because this building might be interesting,” Irving said.

Now, the remodeled building is home to two companies, including an engineering and consulting firm, but still has plenty of reminders of its past, such as its original doors.

With the help of its two-foot thick stone walls, the building is also energy efficient.

For that, Irving credits its original builders of 1842.

"The people who built this took great pride in what they did and used the best materials — it was outstandingly well done,” Irving said.

“In fact, one of the things that greatly helped on this project is, we went to the National Archives and the got the original drawings,” he said.

Margot Sackett of the Historic Sites and Monuments Board of Canada says many of these factors played a role in Tuesday’s announcement.

“We're looking for things that are of national significance, not regional, not provincial,” she said.

“They have to stand out on a national scale, whether its people, places or events — and in this case, it's the place.”

With files from CTV Atlantic’s Mike Cameron