A major boulevard slices through the metropolis, from the working class south to the more affluent north; a journey along this road highlights the many political views of its population.
But US President Donald Trump's recent remarks on Iran have infuriated Iranians across the political spectrum -- regime officials say they have forced the heavily politicized society to close ranks. The country's conservatives are saying "I told you so," while moderates express disappointment at the hard line taken by Trump.
On Friday, after weeks of rhetoric, the US President announced plans to decertify the country's landmark Joint Comprehensive Plan of Action (JCPOA) -- better known as the Iran nuclear deal -- that had eased the country's isolation since 2013.
Trump also labeled Iran's Islamic Revolutionary Guards Corps (IRGC) a "corrupt terror force."
And -- perhaps most controversially of all -- he called the body of water separating Iran from its Arab arch-rivals the "Arabian Gulf" instead of the "Persian Gulf," hitting a nerve in this divided, and diverse city.
The walls here are plastered with Islamic art and portraits of the country's slain soldiers -- but men and women (many of whom wear the mandatory headscarf loosely, a sign of their reformist views) mingle freely in cafes, and downtown an arts scene is flourishing, fueled by the city's liberal youth.
'Trump has done us a great service'
In a dark room lined with religious texts and newspaper clippings, an adviser to Iran's Supreme Leader Ali Khamenei beams.
"Contrary to what other people think, I don't think Trump is against Iran," Hossein Shariatmadari tells CNN in his office at the headquarters of the country's ultra-conservative Kayhan newspaper.
"In fact, Trump has done us a great service. It would have cost us a lot to show that the domestic divisions are beneficial to the United States. Trump did this for us.
"The result is that we have reached more cohesion and unity amongst ourselves," says Shariatmadari, who identifies himself as the "Supreme Leader's Representative."
The US president's remarks, he says, showed America's "true face," explaining that the prospect of sanctions will allow Iran to return to the so-called "resistance economy," a self-sufficient economic system long-touted by the regime's leaders.
As staunch rivals of President Hassan Rouhani
, who sealed the Iran deal during his first term in office, hardliners such as Shariatmadari are fervent critics of the JCPOA.
"Trump's major problem with us is our influence in the region, not our nuclear program," says Shariatmadari, dismissing Trump's remarks as "a ploy to stop Iran's regional activities."
Moderates, hardliners unite against Trump
Perhaps surprisingly, the prominent conservative's remarks have been echoed by some of the most prominent moderate voices in government.
On Saturday, Iranian Foreign Minister Javad Zarif, one of the architects of the nuclear deal and a critic of the country's hawkish Revolutionary Guards tweeted
: "Today, Iranians -- boys, girls, men, women—are ALL IRGC; standing firm with those who defend us & the region against aggression & terror."
In his speech, Trump stopped short of classifying the IRGC as a terror group, despite his previous threats. Instead, he announced plans to impose "tough sanctions" on the elite branch of the country's armed forces, calling it the Supreme Leader's "corrupt personal terror force and militia."
"(The IRGC) has hijacked large portions of Iran's economy and seized massive religious endowments to fund war and terror abroad," Trump said Friday.
Rouhani, whose re-election campaign was openly critical of regime hardliners, also jumped to the IRGC's defense shortly after Trump's remarks. "The Iranian nation has not and will never bow to any foreign pressure," Rouhani said, adding that the IRGC would "continue its fight against regional terrorists."
Iran's stand-off with the Trump administration comes as the country's political power and influence in the region is reaching a peak: it wields widespread influence in Iraq and Syria, and enjoys strong relations with Russia and Turkey.
In addition, it has brought gas-rich Qatar into its political fold
as the tiny Gulf nation squabbles with its Arab neighbors.
Persian Gulf vs. Arab Gulf gaffe
The country's resurgent power isn't lost on anyone, not even the regime's critics.
"We're not a small country. We should stand up for ourselves," student Mona Ragie, 21, tells CNN in Tajrish Square, one of Tehran's socially-moderate neighborhoods.
Many of the moderate Iranians CNN spoke to said they supported Iran's nuclear deal and the access to global markets it affords, but they say that it should not affect Iran's sovereignty, or the ever-present Iranian national "pride."
"My view as an Iranian is that I do not consider (Trump) more significant than a fly," says Hadaytollah Rabiyee. "Why? Because I'm 81 years old and I know that (the US) has always tried to oppress us. We've been threatened for the past 40 years. This country stands like a mountain."
"I like Trump ... he's made people angry with his speech and that's unified people in the world and in Iran," says Hosseini Shakir, 37, a dentist and make-up artist.
For most people here, Trump's biggest political faux pas was in his naming of the body of water wedged between Iran and its Gulf Arab neighbors. Both groups name the body of water after themselves -- it's either the Persian Gulf or the Arabian Gulf -- depending, literally, which side you're on.
But in his speech, Trump called it the "Arabian Gulf" -- apparently taking a side in an age-old naming dispute that the US has traditionally steered clear of.
"This shows that (Trump) is not an educated person and doesn't know anything about the way the world works," says Shuhreh Jaafari, 50. "I think he was paid by the Arab countries."
"One of our rallying points of unity is the 'Persian Gulf,'" explains attorney Momed Sadek Saidi. "By using the fake terminology of the 'Arab gulf,' (Trump) has made us more unified."
"I think some of what he said was OK, but when he talked about the Arab Gulf, that caused the Arab countries to be overjoyed. I got very upset with him because he insulted our history and our nation," says educator Parisa Mohammadi.
Chants of 'Death to America'
Hours before Trump's Iran speech, hundreds gathered at Tehran University, one of the launching pads of the 1979 Islamic revolution
, for the city's most high-profile Friday sermon.
The crowd of worshippers here are some of the country's most religiously devout -- and they are nearly all above the age of 50. Younger people, we are told, stay away from these strongholds of regime influence.
From the pulpit, leading cleric Ayatollah Mohammad Ali Movahedi Kermani urges the deeply conservative crowd to stay true to the principles of the revolution.
"From the start of the nuclear deal we knew that (former US president Barack) Obama was lying and that he wasn't our friend," he says. "The supreme leader showed us that (the US) are not our friends, that they will show their real face to us. They are our enemies."
The crowd erupts into chants of "Death to America," their fists thrown in the air.
Elsewhere in the city, moderate Iranians lament that the US has given hardliners a reason to gloat, and say the US president has extended "the rule of mullahs," as they are known by moderates, for decades to come.
"(Trump's speech) made us realize that if we don't stand together, the enemy would exploit the distance between us," the soft-spoken Shariatmadari says, sitting beneath a portrait of Khamenei.
"A widespread unity was created among us."