The Bank of Montreal is vacating a building that is one of the most iconic in Winnipeg, and a focal point of the famous Portage and Main intersection.

Part of the city's original banker's row, the Bank of Montreal has operated continuously at 355 Main St. for more than a century.

In a letter to clients last week, BMO regional vice-president Kristen Kennedy said the bank is moving staff and operations to a renovated office tower across the street at 201 Portage Ave.

"BMO understands that the building has become an icon in our vibrant community and would like to assure the community that decisions about the building's future will be handled with the utmost care," she wrote.

The move will happen sometime next spring, said Kennedy.

The southeast corner of Portage Avenue and Main Street, showing the Bank of Montreal, is seen in this vintage postcard. (Martin Berman Postcard Collection)

Cindy Tugwell, executive director of Heritage Winnipeg, said Tuesday she was surprised to learn the bank is leaving the building. BMO was an enthusiastic participant in Doors Open, an event that celebrates architecture, and played a "huge" role downtown, Tugwell said.

"I think that's why a lot of us are are a little shocked to hear that they're leaving," she said. "Not only is it a landmark building in the downtown for Winnipeggers, but it's also on the iconic corner of Portage and Main, which is our famous Canadian corner."

The building was designed by architects McKim, Mead & White, according to a 1980 City of Winnipeg report on the building's historical importance, which was also the firm behind famed structures like the original Penn Station in New York City.

An archival photo of the Bank of Montreal building in the 1950s. (Manitoba Archives )

The Bank of Montreal building, constructed in 1913 at a cost of $1.3 million, features six Corinthian columns, weighing 12 tons each, the report says. The exterior was made with granite quarried in Vermont and the interior ceiling is gilded in gold leaf.

"It was supposed to look like a Greek temple when it was built," said Tugwell. "It's significant enough to be one of the top buildings in Canada."

The Bank of Montreal spent millions restoring the building, installing new heating and electrical wiring in the mid-1970s, the city's report says.

The property has a reputation of being well maintained, said Tugwell, but that doesn't mean it will sell easily. She worries the building's future may be similar to other properties along banker's row that became bars and nightclubs.

"Not a best use for that building," she said. "In many cases, they're not maintained as well. They're not utilized every day."

Tugwell hopes 355 Main St. can be converted into public space where people can continue to enjoy the architecture.

"A lot of major cities across North America use buildings of this calibre for art galleries and museums," she said.

"We'll be following this and talking with BMO, and hopefully we'll get some sense as to what was behind their decision and what their plans are going forward."

A man walks past the BMO building at Portage and Main in this archival photo. (Manitoba Archives )

"This is about our customers driving change in what we do and, as they change how they want to do their banking, we're responding," a Bank of Montreal spokesperson said in a statement emailed to CBC News on Tuesday.

"The new location will also bring together retail and business banking as well as wealth teams all in one location, to better support customers."

The Bank of Montreal is also moving operations at its Hargrave Street and Portage Avenue branch to 201 Portage Ave. this spring.

The company is holding a public forum for banking clients in September to discuss the move.