Relatives have placed temporary pictures on the fresh graves, which are yet to be covered by tombstones. (Thomas Erdbrink/For The Washington Post)

The men, tears running down their faces, lifted the shrouded body of Zahra Yousefi, a housewife who died of old age, onto their shoulders. Women in black chadors wailed as they joined the procession that carried their relative and friend to her final resting place, a hot, dusty plain on the southern outskirts of Iran’s capital.

As a cleric led a prayer and the group stood on what resembled a parking lot — with room for at least six other mourning parties to perform rituals simultaneously, each separated by white lines painted on the asphalt — a loud woman’s voice encouraged them to move on.

“Dear citizens, please do not disrupt the flow of funeral processions by remaining in one place too long,” the automated voice urged over an intercom, as hundreds of other people waited to start the same elaborate set of traditions, beginning with a prayer and ending with a burial.

The vast site, called Behesht-e Zahra , or “Zahra’s paradise,” after a female Shiite saint, is the city’s main cemetery, and it is busy, with about 15,000 visitors, and 150 funerals, a day. Over an average weekend, half a million people come to picnic near the graves of family members, famous artists and martyrs from the 1979 Islamic revolution and the war with Iraq.

The cemetery, one of the largest in the world, is also getting crowded underground. In the four decades that Behesht-e Zahra has been receiving the dead, it has become the final resting place for about 1.6 million people. But with the graves filling up quickly and little space left for expansion, the graveyard is running out of room.

The Behesht-e Zahra cemetry is Tehran’s main burial site. Ibrahim Karim, a baker, weeps at the grave of the late ayatollah Mohammad Beheshti, who died along with 71 other high officials in a bomb blast. (Thomas Erdbrink/For The Washington Post)

The cemetery opened in 1969, when Tehran was growing quickly and city officials wanted to limit the practice of burials at shrines and mosques and concentrate them instead in a single location. Two years ago, the city government, which manages the graveyard, built a 200-yard-long underpass to connect it with a new piece of land on the other side of the highway.

Yellow excavators imported from Japan were digging thousands of new graves on a recent afternoon, as laborers worked in more than 100-degree heat. A summer breeze blew in from the nearby desert as mourners buried five people in an area that had only just been prepared to receive the dead.

“In order to be able to use our space more efficiently, each grave now has space for three dead,” said Ismael Daneshpajoo, a spokesman for the cemetery. He took out a map, showing how the management is trying to cram 400,000 dead into the new plot of land.

“The top graves are the cheapest,” at about $150, he said. Graves in older spots of Behesht-e Zahra, where tall pine trees and green bushes have grown over the decades, could cost as much as $10,000. “But it’s really nice there,” Daneshpajoo said.

Officials are vague about exactly when they expect the site to reach capacity. But with all of Tehran (population 12 million) as “clients,” as Daneshpajoo called them, the city is searching for new locations. This is hard, he explained, because people want cemeteries to be close by, but they don’t want to live next to one. “We have two secret locations in mind, but we have to buy them before we announce where they are,” he said.

In the new part of the cemetery, a religious chanter praised one of the deceased, who was just being put into the ground. Two blaring loudspeakers, rented by the family for $45, were in competition with other funerals and their own chanters, and, in the cramped space, all the groups blended into one large collection of mourners.

“Please eat dates and honor the bereaved family of Mahmoud Yazdi,” the chanter sang, as crying family members scrambled to put sand over the last visible parts of the shroud that wrapped the dead.

Iranian authorities have another reason to fill Behesht-e Zahra to the brim: its special place in Iran’s revolutionary history.

When the founder of the Islamic republic, Ayatollah Ruhollah Khomeini, returned to Iran in 1979 to claim his place as leader of the revolution, he gave his first speech on the site to honor those who had died while fighting to oust Western-backed Shah Mohammad Reza Pahlavi.

Today, weekly family visits to relatives’ graves underline the Shiite Muslim culture of martyrdom, which the Islamic republic actively promotes.

The center section of the 580-acre site is reserved solely for those who died defending the country, and for victims of terrorism and assassinations in the years after the revolution. A special cellphone Bluetooth system helps mourners find graves and other locations.

Ibrahim Karim, a 52-year-old bread baker, sat weeping at the grave of Ayatollah Mohammed Beheshti, a revolutionary cleric who was killed in a 1981 bomb attack along with 71 high officials. “He was a great man,” Karim explained, adding that he visited the cemetery every week.

“Those who sleep here are holy for us,” he said. Karim said he didn’t mind that the cemetery is getting so crowded. Even if its graves hold five layers of the dead, he said, he would still want to be buried at Behesht-e Zahra. “Our city is busy, our lives are busy,” Karim said, “so in death we will be used to crowds.”