The only indication that 57 Shahid Sarafraz Street was once Canada's fabled embassy in Tehran is a no-parking sign that mentions it by name, and the distinctive shape of the Maple Leaf adorning the front windows.

The first time the embassy went dark was in 1980 at the height of the U.S. hostage crisis. Canadian diplomats hid six American colleagues and then spirited them out of Iran using fake Canadian identities — and followed them out.

The second time was Sept. 7, 2012. The Harper government was concerned about the safety of its diplomats and wanted to show disapproval of Iran's human rights record, its support for terrorist organizations and its policies concerning Syria and Israel.

This time, after diplomats again quietly slipped out of Iran, Ottawa eventually relinquished control of the building that had been Canada's address in the country since the early '70s — and a vital link between Tehran and the West.

But not before a frantic, "far from perfect" lead-up that was complicated by secrecy, shifting timelines and an airline strike.

embassy

The Maple Leaf on the windows is one of the few remaining hints that 57 Shahid Sarafraz Street in Tehran used to be the Canadian Embassy. (Nahlah Ayed/CBC)

Dozens of documents obtained by CBC News through an Access to Information request provide a glimpse into the complexity and the risks associated with closing down the embassy.

In the often redacted documents, which include emails between staff in Tehran and Ottawa, officials acknowledge Iranian authorities "may retaliate" for the closure by executing one or both Iranian-Canadian nationals in prison at the time.

The same document says allies may privately "lament the loss of a valued source of information" on a country central to regional stability with an important role in Syria's war and beyond.

tehran3

Charles Court, Canada's chargé d'affaires at the embassy in Tehran wrote, 'This close out is far from perfect.' (Nahlah Ayed/CBC News)

But the abrupt break went ahead. And according to several Canadian government officials, it continues to make it hard for the Liberal government to deliver on a promise to raise a Canadian flag again in the Iranian capital.

The episode has caused "a huge hangover effect" on the relationship between the two countries, a Canadian government official told CBC News.

Top-secret exit

Working with a closure "task force" at headquarters in Ottawa, staff at the embassy had a top-secret exit plan to extricate themselves without informing Iranian authorities or Iranian employees until every Canadian diplomat had left the country safely.

That meant destroying sensitive material in the after-hours of an already hectic period, and leaving most other things behind.

Staff also planned to fly out to different destinations in waves to evade suspicion.

The documents suggest the plan took on more urgency when only a week before the closure date, officials suggested moving it up by several days. The reason for the request isn't clear from the documents, but officials familiar with the circumstances say staff security was the primary concern for the government at the time — especially since Canada lists Iran as "a state supporter of terrorism"

mi-iran-ottawa-cp-03222774

Staff back a van into the underground garage at the Iranian Embassy in Ottawa on Sept. 7, 2012, after Canada gave Iranian diplomats five days to leave the country. (Fred Chartrand/Canadian Press)

But leaving early proved impossible because even that close to departure, Canada had yet to confirm a "protective power" — another country that would take on its interests in Iran.

Flights were also heavily booked up.

In a final update from Tehran shortly before secure communication to Ottawa was dismantled on Sept. 6, chargé d'affaires Charles Court wrote: "This close out is far from perfect."

That, he added, "is not surprising given the limitations under which we worked."

Finding a new home

Several Canadian officials interviewed by CBC News say the promised reopening of a Canadian Embassy is significantly complicated by the fact the government relinquished 57 Shahid Sarafraz Street, for which Ottawa continued to pay rent for 18 more months, until March 2014, according to the documents.

In the documents, officials acknowledge the building was no longer considered adequate or secure enough for Canada's purposes.

But without existing real estate to start with, it could take months or longer just for Canadian officials to find an appropriate new home in Tehran, once the decision to proceed is made.

Canadian and Iranian officials first re-established contact last year, and the two foreign ministers met at the UN General Assembly in September.

Homa Hoodfar

Homa Hoodfar, a professor at Concordia University in Montreal, was detained in Tehran's infamous Evin prison last year. Her case sparked a meeting between the foreign ministers of Canada and Iran. (CBC)

Stéphane Dion and Javad Zarif had come together to discuss the case of Montreal professor Homa Hoodfar, who was arrested and interrogated in Iran.

But a significant portion of the discussion was also on concrete steps to move the relationship forward.

"It was quite specific, as far as next steps that could work," said a source familiar with the conversation, who asked not to be identified.

"There is a willingness to move ahead [on both sides] … executing that meeting was crucial."

Slow process

But the two countries have yet to make perceptible progress. There has been no exchange of visits, and no effort has been made yet on the ground to find a suitable building to house a new embassy in Tehran.

"Restoring full diplomatic relations involves a negotiation. It's not simply a matter of declaring that relations have been restored. Both sides have to agree to the terms," said Roland Paris, a University of Ottawa professor and former foreign policy adviser to Prime Minister Justin Trudeau.

"It's a slow process and I don't think anybody expected otherwise."

Progress has also been delayed in part by the election of U.S. President Donald Trump, who has established a harder line on Iran than his predecessor.

Another factor was the replacement of Dion as Canada's foreign affairs minister, which slowed the negotiations.

tehran5

Bahram Ghassemi, spokesperson for Iran’s Foreign Ministry, explains what Canada needs to do to re-establish diplomatic ties with Iran during a press conference in Tehran. (Nahlah Ayed/CBC News)

Iran says the next move is Ottawa's — that it must remove the last of its sanctions before the two countries can proceed.

"We hope these few remaining issues are solved as soon as possible," so that at least the two countries can start by opening representative offices in each other's countries, Iranian Foreign Ministry spokesperson Bahram Ghassemi told CBC News at a news conference in Tehran last month.

The diplomatic void has complicated the lives of ordinary people by making visas and travel documents more difficult to obtain. It has made consular cases harder to solve and limited Canada's ability to influence Iran, whether on human rights, Syria or anything else.

'Serious concern'

A spokesperson for Global Affairs Canada says Ottawa is still committed to re-engagement, but its approach will continue to be cautious. It will depend on Iran's behaviour, including with regard to the nuclear deal it signed with world powers in exchange for the lifting of sanctions.

Trudeau Houston 20170309

Prime Minister Justin Trudeau is taking a cautious approach when it comes to re-establishing diplomatic ties with Iran. (Canadian Press)

Iran is still the subject of "serious concern" but Canada "prefers dialogue over withdrawal," the spokesperson said.

Insiders in Canada and Iran say it's entirely possible that the U.S., Canada's biggest trading partner, could soon clamp down on Iran in a way that might jeopardize the nuclear deal.

That could complicate things for Ottawa. So given Washington's changed tone on the deal, the Trudeau government has adopted a "wait and see" approach, says one official.

What's left

If and when Canadian diplomats return, they will have little to work with beyond vehicles and possibly 25 pieces of art.

Before leaving, staff quietly destroyed sensitive files, hard drives and a stash of emergency Canadian passports, according to the documents.

They delivered an armoured vehicle and $41,000 worth of art from the embassy and the official residence to the Italian Embassy, after Italy agreed to act on Canada's behalf in Iran.

Furniture and office equipment were left behind at the embassy and written off as instructed by headquarters.

Staff were also forced to leave many of their personal belongings.

tehran2

The Canadian government hasn't begun searching for a suitable new property in Tehran. (Nahlah Ayed/CBC News)

The escape from Tehran was almost derailed when, facing strikes, the German airline Lufthansa cancelled thousands of local and international flights just days before the scheduled closure.

In his final update from Tehran, chargé d'affaires Court wrote that the strike "has complicated departure scenarios." Officials did manage to find other flights at the last minute.

He ended his final email by noting the "emotional and professional challenge" for Canadians in keeping the plans from Iranian staff, and their hope those staff "are treated with all the consideration and generosity possible."

The documents included a procedure for contacting local staff to inform them of the decision and to arrange for final payments. Global Affairs says that part alone cost $1.3 million in severance and pension payments.