TEHRAN — The biggest danger in Tehran is "crossing the street," says my Iranian friend Nozhan, who lived in Europe 12 years before returning in 2013 to the megalopolis that is Iran's capital.

He knows that as a Westerner, I am unnerved by a range of threats I have come to associate with the Islamic Republic. Now that I'm here, I realize most of those ideas are unfounded. Nozhan's advice, on the other hand, proves to be quite sound. "Avoid the zebra crossing in particular," he advises, because cars "accelerate instead of slowing down" when they see pedestrians using them.

Public transport, consisting of buses and a metro, is modern and cheap in Tehran. But it is insufficient for the 10 million people moving around from Saturday to Thursday, the Iranian workweek. Most drive a car or use phone cabs, or "shared" taxis that can take up to four or five passengers. The result: crazy traffic.

Add to these a fleet of "informal" taxis or people taking passengers in their cars to earn extra cash (many are commuting employees), and negotiating fares with passengers. You will particularly see them hawking in the morning and evening rush hours, driving around looking for passengers on the right-hand side of the road, or even double- and triple-parking outside stations, loudly announcing a direction like peddlers in the Bazaar.

It doesn't help that the city is almost without traffic lights. The few that do exist, with their tremulous orange light, work intemittently. An overly cautious pedestrian could wait hours for the right moment to cross the street. The only option is to venture out with a mix of caution and recklessness. That instils respect from oncoming cars, forcing them to either slow down or swerve around you.

Parched in public

Another danger foreign visitors to Tehran face is ending dehydration and heat stroke. In late June, the thermometer reaches 40 very dry degrees celsius, in a very polluted city. In the month of Ramadan, it is forbidden to eat, drink or smoke in public from sunrise to sunset. Thus all cafés and eateries are closed until evening. You can buy a bottle of water, but taking a sip in view of anyone can mean trouble with the police.

Inside one can eat normally, but that is tricky for a foreign visitor, who doesn't have a home to duck into. At one point, overcome by the heat and thirst, I just can't stand it anymore. Nozhan starts talking to a grocer who lets us go to the back of his shop, where he offers us water and fruit.

A refreshing few minutes later, after eating some cherries and a banana, we chat a bit out of courtesy, with Nozhan translating. The warmth and friendliness of the people is apparent beyond the insuperable language barrier. After a while the best thing is to keep quiet and listen to them speak among themselves, appreciating the musical quality of Persian, with its opaque sweetness. Before going we try and pay, but the grocer will have none of it. How could he charge for giving us refuge, he asks?

Currrency confusion

Another good afternoon refuge is one of the museums (Tehran has excellent historical museums and one of contemporary art with, unexpectedly for me, pieces by Jackson Pollock, Francis Bacon and Warhol, among other artists), or the Grand Bazaar. Its alleyways are shaded and cool, an unending labyrinth of little shops and kiosks selling anything from cheap trinkets to sumptuous carpets.

How much do things cost? Difficult to say for sure. The official currency is the rial. All banknotes carry Ayatollah Khomeini's face, with writing in Persian and Arabic numerals. But people speak and think not in rials, but in tumans — a tuman being 10 rials. Rials replaced tumans in the 1930s, but both are used today, and that may confuse foreigners. The price tag says one thing. The seller says another.

Here and there, in corners of the Bazaar or in a park, you may find the odd person furtively violating the Ramadhan fast, ever alert to possible police presence. What is not violated in public, however, are clothing norms. Men cannot wear shorts. Women cannot wear clothes that reveal parts of their body or are too tight (revealing their form), and must cover up at least their nape and ears. Some are uber-covered, with a body-length black cloak or chador.

Strolling in a middle-class type shopping center, I notice the number of women who have had nose operations. There are a lot of "perfect noses" and numerous signs of recent, face surgery. It is not surprising, since the nose and face is all they can show in public and these inevitably become their only tools of seduction.

Behind closed doors

Indoors, people do as they please, in all areas. Women in miniskirts, topless men, widespread use of recreational dope and soft drugs just to cite some examples. The blatant divide between public and private is typical of this country. Homes play the role of a social veil, and even the smallest ones are to some extent, private palaces or fortress.

As the afternoon progresses, pedestrians take on a ghostly aspect. The fast reaches an almost unbearable point just before sunset, when you pray and can eat and drink. Not alcohol of course. Apart from a few specimens of home-made wine drunk indoors, alcohol is notably absent, even as so many bottles of water in Tehran homes are clearly, former bottles of whisky and vodka.

As prayers begin in the city's mosques, there is a sense of imminent relief. People come out with ice boxes or portable samovars, looking for a place to lay out a rug and "chill out." Nozhan insists we go to the Ab-o-Atash (Water and Fire) park. He says I must see the Nature expand=1] Bridge recently opened over one of the city highways, linking this to the larger Taleghani Park. "It's much prettier than the New York High Line," he says proudly. He is proud of Iran, and of himself for having traveled so much in the 10 years he was in the Netherlands.

It is night time, and friends and families fill the park. Its main attraction is a system of fountains and two towers with fire burning at their tips. People move away from the busy paths, looking for secluded spots to lay out a carpet. Leaving their shoes on the grass, they settle to eat, drink, smoke, and recline and chat for hours in the cool of a Persian night, as their ancestors must have done.

Nearby, the bridge's ultramodern silhouette stands out against a gleaming motorway where the mighty traffic rumbles on. Nozhan was right: It is somehow enigmatic and quite simply magnificent.