I have always been drawn to those who are dangerous in some way: those who love too passionately, who think (and act) too radically, whose imaginations are easily heated to incandescence. So I should not complain when I get burned and lose everything. We need to experience the “Grand Passions” at least once in our lives. We need to live life at white-hot heat to feel that we are truly alive and human. “I am alive, therefore I bleed. I am human, therefore I weep”.

But what I value more than the “grand passions” of Life is a subtler form of emotion that is paradoxically more potent than passion. I hesitate to call it “tenderness” because that word has other implications, but I have no other word large or clean enough to describe it. Physical consummation is no more than a crude metaphor for this Love. It flows from the most vulnerable places in us, those of least resistance which, I suppose, we have to call the “soul”. It is expressed in a gentle touch of hands, in a heartfelt hug, or a wife sewing on a button to her husband’s shirt.

As with interior landscapes, so with physical ones. There are places that proclaim their religious and artistic passion with loud fanfares of architectural bravado: places such as Esfahan and Mashhad. But other (quieter) spaces woo the visitor in subtler ways that are ultimately more potent. I am thinking of places such as Natanz in Central Iran.

Forget all about stories of nuclear complexes, underground chambers and uranium enrichment centrifuges. There is far more to Natanz than pears and conspiracy theories.

The ancient town of Natanz lies on the Qum to Yazd road, skirting the mighty Kavir desert. It is a green oasis surrounded by mountains and shielded from desert winds by an amphitheatre of rock that resembles a rampart of teeth. The traveller, coming upon it in mid-summer, might let himself believe he is approaching a paradise. For Natanz arises out of the dust haze as if from some vision, or from the depths of unconscious experience: a green plain stretched out like a vast Persian carpet before his incredulous eyes.

It is a place rich in legends. Long before you even enter the town, your attention is drawn to a strange domed building perched impossibly high on a slender pinnacle of rock thousands of feet above the road.

The story goes like this. There was once a king who loved hunting, and on one of his expeditions to Natanz, he stopped at a small stream to rest. As he leaned over the edge to drink, his hunting hawk swooped down over his head causing him to flee for cover. After a few minutes he returned to the water, and once again the bird dived at him, dislodging a cup from his hand. The king cursed the bird and made efforts to retrieve his cup, and this time the falcon struck him forcibly on his cheek, drawing his royal blood. Incandescent with rage, the king ordered the bird to be shot down immediately. Then, when the bird lay dead at his feet, he returned to the water in peace. But as he leaned over to drink, he heard something rustling in the bushes beside him. Pushing aside the layers tangled branches, he saw a poisonous snake slithering away into the shadows. And at that moment, in a flash of insight, he realized that the hawk had been trying to warn him of this danger. By its actions, it had quite possibly saved his life.

Grief-stricken, and swaying under the enormity of what he had done, the king ordered a mausoleum to be built for his faithful falcon. He chose the highest outcrop of mountain overlooking Natanz: a thin needle of rock cleft from the side of the lofty Kuh-e-Karkas. To build it, masonry had to be carried on the backs of sheep, the only animals capable of reaching the precarious summit. And there to this day, it stands as a monument to the king’s most loyal servant: an octagonal tower crowned by a marble coloured cupola high up in the Natanz sky.

Locals love to tell visitors the story. But they also add that it is entirely fanciful. Kuh-e-Karkas means the “mountain of vultures”. It is a reminder of the days when the region’s Zoroastrian inhabitants laid out their dead on the tops of lofty mountains for vultures and other creatures of the air to dispose of. The Natanz tower was originally a Zoroastrian structure, they say, a fire altar or a dakhma (a “tower of Silence”), and not a mausoleum to the memory of Shah Abbas’s falcon.

But in Natanz, things are rarely what they seem. There is a tantalising ambiguity about everything here. Literal facts are secondary to other, less accessible, truths. The important element in the falcon story is not its historical accuracy, but its lesson about good and evil, faith and distrust, service and sacrifice.

In the same way, a local Natanz legend stubbornly maintains that the last Achaemedian King (Darius III) met his end in these hills, pursued by the armies of Alexander. They ignore all the many historians who unanimously locate the site of Darius’s death much further north (near Semnan). For the people of Natanz, however, Logic is too confining to be followed religiously.

It takes a little time to adjust yourself to this idea. But once you do, you can make your way immediately to the khanaqah, or dervish monastery, situated on the outskirts of the town. Do not be misled by its tranquillity. This building is a dangerous love affair, a smouldering passion.

The complex began as an octagonal pavilion around the grave of some unidentified saint buried in the last years of the 10th century, perhaps an imamzada or shrine for the descendant of the prophet. In the 13th century a little-known Sufi mystic, Abd al-Samad (a disciple of Suhrawardi), came to be buried there; and in the years that followed, a whole cluster of little religious buildings grew up around his grave. For centuries travellers were given hospitality here, irrespective of their religion or their class.

For the Sufis who built this place, truth was not a verbal explanation, or even a divine image, but a particular way of living and perceiving. They criticised those who held blind beliefs, those who loved and cherished their conceptions of God more than the real thing. They hated all kinds of rigid intellectual theology which (they believed) often concealed the subtlest form of atheism. And as a result, they built their monastery with a measure of ambiguity and hesitation. Nothing about it was allowed to be absolutely regular or definite. Everything was made to reflect a poetic imprecision, or “negative capability”.

Standing in front of the main doorway, completely blocking its entrance, is an ancient plane tree over eight hundred years old. It was planted deliberately at the same time that the khanaqah was built. Its twenty-two trunks lean forward like a procession entering the shrine. It provides some welcome shade for parked cars and motorcycles. But originally, the tree was an integral part of the building. Indeed, its roots have become so entangled in the foundations now, that building and tree constitute one indivisible organism.

The purpose of the tree is evident. It stands in front of one of the most spectacular architectural facades in all Iran: a dazzling kaleidoscope of coloured glazed tiles, pastel-coloured stucco and terracotta symbolism. Some of the geometric patterns are recognizable as scientific symbols; others have become trademarks of Western companies like Mercedes Benz. The shadows of the leaves tremble on the fevered blues and pinks like the fluttering wings of a thousand birds, changing their qualities from moment to moment, granting them a joyful, shimmering kind of life. They breathe out colour, softening the lines of the stones, blurring the geometric patterns, creating a hypnotic effect that is sheer magic.

Inside the monastery there could once be found one of the largest and most lavish mihrabs in all Iran: a masterpiece of craftsmanship unrivalled anywhere in the world. In the nineteenth century, however, British adventurers (i.e. thieves) tore it wholesale out of the wall and transported it off to England. Then they ripped out the magnificently carved entrance door and carried that away as well. Today they are both unashamedly on display in the Victoria and Albert Museum in London.

Over the years, other visitors came and (one by one) took away the famous glazed tiles around the saint’s tomb. Decorated with delicate calligraphy from the Koran, they were emboldened in a subtle variety of pastel blue shades. Some had figures of exotic birds sitting amidst lush foliage, their heads defaced by later religious zealots, (which makes them easily recognizable today in the displays of Western museums).

Despite its fate at the hands of such looters, this remarkable building somehow managed to retain its dignity and fascination. Academics continue to write volumes about it. But poetry resists academic pretensions, just as the mystery of religious faith evaporates on contact with dogma. Here, more than in the mosques of Esfahan or Mashhad, it is still possible to experience the occasional “lifting of the veil”: - as long as one enters without guides and without preconceptions.

In the middle of the courtyard is a series of steps descending into a deep qanat whose waters are considered holy. When I visited the complex recently, there was no-one there. I descended alone to wash my hands and face. Then I took off my sandals and entered the tiny mosque behind it. As I stood there, light fell onto my hands from somewhere far above my head, and for a moment the presence of something supremely precious and powerfully benign beamed down upon me.

The Sufi brotherhood that built this remarkable building found wisdom in all the religions; and all were respected. For hundreds of years they lived shoulder to shoulder with the Zoroastrians, whose fire temple stood just metres away from them. Today, its Sassanian stone arches can still be seen rising above the ruins of the adobe houses surrounding it. Generations of Zoroastrians worshipped here until quite recently, (apparently peacefully), until their community died out, or were converted to Islam.

The little town of Natanz is an oasis for the spirit. It is a pity that today it is virtually ignored by tourists, and known only to the world for its controversial nuclear power facility, 30 miles away in the emptiness of the Kavir desert.