"In the name of God, the compassionate and the merciful, welcome to this Iran Air flight to Esfahan." To say that I am a nervous flyer would be an understatement. So imagine my terror at being strapped inside a 30-year old Boeing 747 about to take off on a 40-minute flight from Tehran to Esfahan in central Iran. I knew it didn't have any spare parts because it said so in the Iran Daily on my lap, in which the Iranian minister for roads and transport accused the American trade embargo of "endangering the lives of passengers".
In front of me was a sea of Hermès scarves, on the heads of the Iranian women who had forked out the equivalent of £20 for the heavily subsidised return flight. The air stewardess, dressed in a stylish bottle-green scarf topped with a cap, soothed our nerves by switching on pleasant mood music, which thankfully continued until well after take-off. Less than an hour later we had been transported to one of the most magnificent Islamic cities in the world.
I was an accidental tourist in Esfahan. A small group of Western journalists had been invited by the government to tour Iran's most sensitive nuclear sites. But when we arrived in Esfahan on the first leg of the tour these plans immediately began to unravel. We were informed that after an afternoon's sightseeing, we would spend part of the next day visiting a steel plant instead of a scheduled visit to the uranium enrichment facility at Natanz. Needless to say we rebelled, and Jafaar, the government representative in Esfahan, became our unofficial tour guide to his home city.
I had long wanted to visit Esfahan, once the capital of Persia, but had not been prepared for such splendour. The Persians called it Nisf-e-Jahan, " half the world", meaning that to see it was to see 50 per cent of all the worthwhile sights on earth. The city, framed by spectacular jagged sandstone mountains, is an oasis in the desert, and is therefore surprisingly green, cut through with an elegant garden boulevard lined by plane trees.
Our first stop was the "40 pillars" palace of Chehel Sotun. The name arises because its 20 carved wooden pillars holding up an intricately inlaid ceiling are mirrored in a long reflecting pool, set in a park of cawing grey crows. Inside the palace is one of the surprises of the Islamic republic: among the frescoes is one of a topless maiden. The paintings survived the 1979 revolution thanks to the protection of the palace caretakers.
We had stumbled on one of the paradoxes of Iran, which seemed to me like a curious mix of America and the Soviet Union. Behind closed doors, middle-class Iranians are dressed in the latest Western fashions, enjoy a glass of black-market wine, and watch satellite television. Yet outside they are subjected to the watchful eyes of the state's repressive security apparatus, while women can be threatened with jail for showing too much hair under their hijab.
Westerners are expected to observe the dress code in Iran. In addition to a headscarf or shawl, you need to wear a long-sleeved, shapeless, lightweight overcoat that comes to your knees – if you can find such a thing in summer. I was lucky because a friend brought me a cheap black manteau – a cotton overcoat – from the Tehran bazaar, which I wore over jeans or trousers. (The alternative would have been a borrowed rubbery black Dannimac, rather inappropriate in the heat.)
On the flight from London to Tehran, it had been quite a sight to see the plane transformed into a giant changing room when we touched down, as Iranian women in full make-up and skimpy clothes put on their scarves and overcoats, smiling at each other in silent complicity. The strict dress code, in force since the revolution, makes itself felt everywhere in a kind of sexual apartheid, from hotel swimming pools – where mixed bathing is strictly forbidden – to separate entrances for men and women in the airport departure area. This is where Western women are most likely to have their scarf yanked forward by a forbidding old crone in a full-length black chador, as happened to me.
And yet the Islamic Republic of Iran, where the population is mostly Shia Muslim, is unexpectedly discreet in its religious aspects. Although every office contains portraits of the Ayatollah Khomeini and the current supreme leader, the Ayatollah Ali Khamenei, you don't hear the call to prayer from countless minarets as you do in the great Arab cities. I heard more Islamic ring tones on mobile phones in predominantly Sunni Muslim Egypt than I did in Iran.
After a copious lunch of salad, including a plate piled high with fresh basil leaves and walnuts, and kebabs washed down with alcohol-free Bavaria beer, we piled into our air-conditioned coach. Jafaar took us to the heart of Esfahan, Imam square, dating from the golden age of Persian architecture under the ruthless and bloodthirsty Shah Abbas the Great.
The square – once used as a polo ground, as you can see from the marble goalposts – is stunning. Its uniform two-storey buildings embrace some of the most impressive Islamic monuments in the world, as well as the bustling bazaar. Sweating under our hot scarves and overcoats, we climbed up a spiral staircase to a pillared terrace in Shah Abbas's Ali Qapu palace, from where he used to watch the polo matches, and we viewed the full majesty of the square. Opposite us was the miniature private mosque built by the Shah between 1602 and 1619, which you enter through a twisting corridor. But the square is dominated by the blue-tiled dome of the Imam mosque, which the Shah managed to see completed just before his death.
Jafaar was pressing on. We followed him higher up the spiral staircase until, red-faced and puffing in the oppressive heat, we arrived in the music room on the palace's seventh floor, where the musicians would entertain royal guests from behind an intricately carved wall.
"Why did the Shah build a spiral staircase?" asked Jafaar. We were still gasping for breath. "For security reasons. A single swordsman could protect his master by swinging his weapon in his right hand from the top of the stairs, but those coming up would have to fight with their left."
But Jafaar kept his best party trick for the Imam mosque. After entering through the portal, past its swirling calligraphy, you have to turn a corner into the mosque, which was built to face Mecca. "Listen to this," he said, and stamped on a central paving stone under the great dome. The echo went on and on – up to 17 times, he said. We all joined in the fun. Jafar invited a little girl to do the same, and her shy whisper reverberated again and again. "They built it with the echo because if you do a good thing it reflects on you, or if you do a bad thing it will too," Jafaar said. "So it means – think about what you're doing."
It was time for a break. We joined the sweet-toothed Iranians queuing up for ice cream, and drank pomegranate juice on the grass. As the tourists returned to their hotels, Iranian families began to gather at the end of the day to picnic; some assembled rudimentary gas stoves. A girl in a headscarf skated in circles on yellow roller-blades to the amusement of her friends. Small groups, including some women dressed in the chador, hired a horse and carriage and recorded their ride through the square on video.
By 8pm it was getting dark, but Jafaar hadn't finished with us yet. We were driven to the Khaju bridge, which stands over the gushing turquoise waters of the Zaindeh River, along roads jammed with traffic as the locals headed for the riverside. Despite the gridlock, we were told that the number of motorists on the road had decreased since the government brought in petrol rationing at the end of June. According to Jafaar, the bridge is the best place for summer picnics, as a cool breeze runs through its arches, built on two levels by Shah Abbas II on the spot of a former caravanserai.
While most people were content to sit on the steps of the illuminated bridge, we saw some Iranians stroking one of the two lion statues on each side. "Look, the lion's eyes glow in the dark," said Jafaar. It was the eerie reflection from a yellow street lamp. Further along the river's curve, where a fountain plays, Iranians hired little boats with swan necks in a scene straight out of Wagner's Lohengrin, minus the music.
It was time to head back to our hotel, the luxurious Abbasi, where dinner – delicious barley soup, more salad, kebabs and a bright pink mayonnaise mysteriously called French dressing – was served in a garden courtyard. Only then could we return to our rooms to rip off our hot shawls and overcoats.
The next day, our tourist treat continued. First up was a visit to the city's Armenian quarter and Vank cathedral, whose sober exterior contrasts with astonishingly gruesome frescoes inside depicting the martyrdom of saints. Shah Abbas I, who unified the country, deported hundreds of thousands of Armenians to Esfahan during a scorched-earth campaign, and several thousand still remain in the city, although many families have left for the United States.
Inside the cathedral complex stands the Armenian museum. In addition to a drawing of a bearded man, attributed to Rembrandt, the museum contains two unique exhibits. An Armenian had managed the extraordinary feat of writing on a woman's hair. You can view it through a microscope. The other curiosity in the museum is the world's smallest book, an object the size of a microchip that weighs 0.7g and contains, we were told, the Lord's Prayer in seven languages.
Next on our tour was the Friday Mosque, a sprawling complex rebuilt after a fire in the 12th century, which has been described as a museum of Islamic architecture through the ages. Esfahan, invaded by the Arabs, the Afghans and Tamerlane in its long history, has luckily escaped a major earthquake. But the city lives in fear of a tremor such as the one that flattened the ancient town of Bam on the old Silk Road. When we visited Shah Abbas's private Sheikh Lotfollah mosque, Jafaar pointed out a row of wooden bricks just above our heads, laid in hopes of protecting the building from an underground jolt.
As we entered the Friday Mosque, people were beginning to gather for prayers, the women separated from the men by thick cotton sheeting. The Shia pray three times a day, with the last prayers taking place half an hour after sunset. In winter, prayers are held at the Friday Mosque in an underground chamber lit by alabaster skylights.
A woman followed us out of the mosque. As she adjusted her chador, I caught a glimpse of her smart black trousers and beige and red jacket underneath. She snapped open a red mobile phone as she headed into the bazaar. It was another image of Iran today.
On our last evening in Esfahan, we shook off our minders. It was time to hit the bazaar. No sooner had Jafaar disappeared into the darkness than a tall young man with typically Iranian grey eyes sauntered over and struck up a conversation. "Welcome to Iran," he said to me and my two female companions. "Are you German?"
You might expect Iranians to be wary of the British, as we seem to be blamed for many of their woes (although it was Saddam Hussein who most recently attacked Esfahan, when a rocket slammed into a mosque during the Iran-Iraq war). The UK did, of course, plot to overthrow the first democratically elected Iranian leader, Mohammad Mossadegh, in the 1950s, after he nationalised the Anglo-Iranian oil company. But the average Iranian reaches out to foreigners across the language barrier, including the British.
Hamid, who worked for one of the carpet-sellers in the bazaar, guided us to the "best" pistachio store, where sacks full of nuts, dried figs and sultanas were piled high. There were beautifully decorated tins containing a kind of cashew-nut brittle in a delicious caramelised sugar.
Hamid asked whether we had been to a teahouse. Esfahan is renowned for its ancient teahouses, where Iranians sit for hours contemplating life in front of their hookahs.
We followed him down alleyways behind the bazaar and finally through a tunnel emerging into a courtyard. Suddenly, I heard a loud whooshing noise and saw a burst of flames. I began to wonder whether we would need to call the tourist police, whose white-and-green cars are parked at the main tourist sites, but it was only a metalworker plying his trade in the courtyard. We descended a few more stairs and found ourselves in the oldest teahouse in Esfahan, where we could see lines of men drawing on their hookahs on the other side of a curtain.
Mixed hookah sharing was banned a few months ago, when the mullahs realised that young Iranians were seizing the opportunity for physical closeness with the opposite sex. But the teahouse made an exception for Western visitors, and a steaming pipe was brought to our table.
At the next table was a woman sporting one of the accessories of seduction in Iran: a bandage over her nose. With the veil covering much of a woman's face, it seems that a nose job is as important as a Hermès scarf.
After the teahouse, we successfully tracked down a selection of papier mâché pomegranates, and visited a store specialising in reasonably priced handmade tablecloths whose colours are fixed by being washed in the river. After settling up in cash – even the hotels don't take credit cards – we could no longer ignore Hamid's invitation to his carpet store. At the Paradise carpet shop, the owner was happy to flick through a book on Persian rugs and talk about the nomads who only sell their carpets when they need the money.
I didn't bring back a rug, but I did buy a tablecloth and napkins, some salted pistachios, and a blood-red papier-mâché pomegranate for around £1.50. I also came back with a mosquito bite on my ankle, two buttons missing from my overcoat, and a few grey hairs from those Iran Air flights.
Tehran is served by Iran Air (020-7409 0971; www.iranair.co.uk) from Heathrow and by BMED on behalf of British Airways (0870 850 9850; www.ba.com). Cox & Kings (020-7873 5000; www.coxandkings.co.uk) offers an eight-night "Treasures of Persia" trip from £1,371, including flights from Heathrow, transfers, B&B, some meals and sightseeing.
Abbasi Hotel, Esfahan (00 98 31 226010; www.abbasihotel.com); from US$140 (£70) double, including breakfast.
The Foreign Office (0845 850 2829; www.fco.gov.uk) advises: "There is a general threat from terrorism. Explosions have killed a number of people since 2005. Attacks could be indiscriminate, including in places frequented by expatriate and foreign travellers." British passport-holders require a visa, obtainable for £68 from the Embassy of the Islamic Republic of Iran, 16 Prince's Gate, London SW7 1PT (020-7225 3000; www.iran-embassy.org.uk). Travellers with evidence of having visited Israel, e.g. with an Israeli stamp in their passport, will be denied entry.