By all appearances, the Haskell Library and Opera House is an unlikely place to smuggle firearms, if anything at all.

The Canada-U.S border between Stanstead, Que., and Derby Line, Vt., that the 113-year-old building sits on is defined by a row of flower pots on the street next to the library and a border patrol car idling nearby at all times. 

"It really was just one community that happened to have an imaginary line drawn through it," Nancy Rumery, the library's director, told CBC News.

The small town vibe made it easy for Rumery to notice something was amiss on March 25, 2011, when three suspects entered the library to exchange a backpack filled with handguns.

"We're not afraid of strangers or anything, but it stands out ... these people from the outside stood out and were noticed, and attention was paid to their activities," she said. 

Now six years later, the U.S. Attorney's Office in Vermont has announced Montrealer Alexis Vlachos, 40, has been extradited to the U.S. to be tried.

Vlachos was indicted there on five counts in 2015 and pleaded not guilty in federal court in Vermont earlier this month. He's being held there pending trial.

Entrance in U.S.; books in Canada

The library, a mix of Victorian, Georgian and neo-Classical-style architecture, was deliberately built on the border to serve both Canadians and Americans in 1904, four years before laws forbidding new structures built near the perimeter were enacted. 

The Border Line

A black line on the floor marks the international border between the United States and Canada at the Haskell Free Library. (Toby Talbot/Associated Press)

The perception of the border has changed under U.S. President Donald Trump, who continues to push for a wall in Mexico and tried to halt immigration from a number of majority-Muslim countries, causing asylum seekers to risk their lives crossing into Canada in the dead of winter some 100 kilometres away in Hemmingford, Que. 

But Rumery says she's grateful the library is still accessible to people from both sides of the border. Its only entrance is on the American side, so Canadians can walk inside without having to go through a port of entry. 

The circulation desk and books are in Canada and "reading room is international," according to the library's website. Inside, a line of black tape tells you which country you're in. 

Rumery says the only doors on the Canadian side are emergency exits without handles on the outside. 

Prosecutor can't recall similar case

According to a statement issued Tuesday by the Department of Justice, two "co-conspirators" hid the backpack filled with handguns bought in Florida in the bathroom, where Vlachos retrieved it.

"It's a stressful thing. The adrenaline certainly starts coursing through your body, but I guess I'm more concerned about the safety of my patrons and their continued access to the things that they need at the library," Rumery said.

The prosecutor in the case, Assistant U.S. Attorney Joe Perella, said no other smuggling case at the library came to his mind.

"In my 20 years at the U.S. Attorney's Office, it's the first case of gun smuggling at the Haskell Library," Perella said in a phone interview.

He said the library was a "really special" community tradition and that "it's unfortunate that a gun smuggling case like this can undermine trust."

Rumery says she's satisfied with the security at the library so far, though, and by the fact the alleged smugglers were caught in what she calls one isolated incident in the institution's more than 100 years. 

The Border Line

The opera house on the second floor of the library was created in honour of the Haskell family. Its stage is in Canada and most of the audience sits in the U.S. (Toby Talbot/Associated Press)

The library was founded by residents of the community on both sides at the turn of the 20th century to honour the local Haskell family, she explained. 

Several buildings in the towns straddle the border, but the library is the last public one.

"We're kind of the last place where Americans and Canadians can meet and mingle and interact," she said. 

With files from The Associated Press