TEHRAN, Iran — Her hands tightly wrapped around a giant penis-shaped tombstone, Maryam giggles as her friend takes a picture. She repositions herself and, snap, another photo.

She’s one of the hundreds of tourists who come to visit Khalid Nabi cemetery, a place replete with contraditions. In this conservative Islamic country, it is a historic cemetery where male and female genitals are on display for the world to see.

And now, despite being hundreds of years old, it is becoming one of the country's hot new tourist destinations for young people. More than 600 head stones make up the bizarre cemetery, which is 40 miles northeast of Gonbad-e Kavous in northeastern Iran. Despite its long history, the site was only added to Iran’s national heritage list less than a decade ago. And even since then, few researchers have dared to study it.

Visitors from all over the country — and even the world — are now coming to this mountainous area of Turkmen Sahra, which is on the border with Turkmenistan, to see for themselves the collection of stone genitalia. They can book a tour through a local travel agency, and Kahlid Nabi is only a bus ride away.

Getting to the spectacle, however, isn’t particularly easy. The road is unpaved and there are hairpin turns, not recommended for the faint-hearted. But once there, the site doesn’t disappoint. In spring — the best time to visit — endless lush, green hillocks line the horizon.

Atop one of the surrounding peaks, a shrine towers majestically. It is thought to house the tomb of Khalid Nabi, a prophet born in Yemen 40 years prior to Prophet Muhammad, according to Alireza Hesar Nuee, one of the rare historians to have studied the site. According to Hesar Nuee, Khalid Nabi promoted Christianity in several countries in the region, including Iran.

Even though Khalid Nabi himself was Christian, years later, his daughter visited Prophet Muhammad and converted to Islam. That is when Nabi’s tomb was placed upon a high mountain and revered as a sacred pilgrimage destination.

To this day Turkmen women tie ribbons to the branches of a tree near the shrine as a pledge for resolution for their troubles. Turkmens live in Iran’s northeast and speak a different dialect from Persian. They live a mostly nomadic life, making a living from training horses.

A few hundred meters from the shrine, in an uninhabited (and increasingly uninhibited) valley, is the mysterious cemetery. There are two types of tombstones scattered across the slope — long columns, some of them as high as two meters and topped with a hat that, clearly, represent penises and smaller headstones similar to a cross that some think represent female breasts.

Hesar Nuee said the tombstones are symbolic representations of male and female genitals. He said the symbolism could come from the phallic religion practiced in India and central Asia, but few know for sure the meaning behind the designs.

The chatter among tourists, often overexcited by the surprising sight, is the only thing that breaks through the otherwise perfect silence of the cemetery and the valley. The bashful are hesitant to take pictures standing next to the poles, but others see it as an opportunity to have a laugh.

On one recent afternoon, a debate broke out about why some of the penis tombstones are shorter than others. While some believe it could reflect the age of the deceased, one insists that it’s due to "shrinkage."

“Here, it feels like standing on the top of the world,” Mehdi, a tourist from the Iranian city of Isfahan, said on his visit to the shrine, adding that he didn’t know the cemetery existed until he heard a group of friends talking about it.

Khalid Nabi first gained notoriety in a scholarly article published by David Stronach in 1981. In it, Stronach introduces the site and mentions the lack of research on it.

But after that, Khalid Nabi was again quickly forgotten. Nowhere was it mentioned until nine years ago when interest in the site surged as tourism in Iran boomed. The increase in tourism was in part spurred by Iran’s younger generation, which saw short trips out of the city as way to meet and mingle with others, something that can often be difficult under the watchful eyes of Iran's morality police.

The more remote and obscure the place was, the better.

And as tourism began to increase, so did the cemetery’s oddball reputation. Professional photographers began taking pictures of Khalid Nabi, publishing them in various outlets. Some blogged about it and word began to spread.

On the bus ride to Khalid Nabi, many tourists complained about the censorship that has surrounded it over the years. “This is part of our culture and history,” one said, “why should it be ignored?”

While many cities in Iran are expanding rapidly and many Iranians are getting caught up in the urban hustle and bustle, Khalid Nabi remains detached and frozen in the past.

It remains for researchers to explore, but for now, to many average Iranians, it makes for a good laugh.