People who want to visit the U.S. Embassy on June 5 or 6 will have to pre-register. Only 500 people will be allowed inside. (Emily Chung/CBC)

The U.S. Embassy will take part in Doors Open Ottawa for the first time, inviting local visitors past the security barriers and inside the building.

Doors Open is an event that has taken place annually in Ottawa since 2002, allowing visitors to enter and explore many buildings normally closed to the public. In the past, those buildings have included the embassies of Croatia, Hungary, Brazil and Algeria, but never the imposing building on Sussex Drive that houses American diplomats.

David Jacobson, who was appointed U.S. ambassador to Canada last fall, said the embassy is part of the community and wants to be more neighbourly.

"I represent a president and an administration that believes in openness and transparency and this is a part of it," Jacobson said, adding that many people view the embassy to be cloaked in mystery.

"And it's not. And that's part of the reason we want people to come in."

The building is surrounded by metal fencing and concrete barriers, but Jacobson said embassy staff want visitors to see it is an office building where people work on developing the relationship between the United States and Canada.

The Doors Open committee has worked for nine years to get the U.S. Embassy to participate, said Carolyn Quinn, a longtime committee volunteer. The embassy has always declined, citing security reasons.

But this year, the embassy called the committee and asked if it could take part.

"And of course, it was a no brainer," Quinn said with a laugh.

She said she considers the addition of the building to the Doors Open program "a coup." Organizers said they often hear from people who would like to see the inside the embassy.