Photo: Schezar, via Flickr

On May 28, 1453, the Byzantine emperor Constantine XI entered Hagia Sophia, “the church of the divine wisdom,” to pray. Constantinople was under siege, and the fate of the great basilica was unclear. The emperor prayed there before returning to the city walls, where he coordinated the defense effort against the army of Mehmed II, who would be christened conqueror by day’s end.

As the two armies struggled to outmaneuver each other, those caught inside Hagia Sophia waited anxiously, fearful of what might happen if the capital of Greek Orthodoxy fell into Muslim hands. Emperor Justinian had commissioned the church in 532 A.D.; planned by the mathematician Anthemius of Tralles and the physicist Isidore of Miletus, and built by more than ten thousand laborers, it was intended to symbolize the magnificence of Christianity and become the seat of the Orthodox patriarch. Twenty years after its completion, two major earthquakes shook Hagia Sophia and destroyed its eastern arch. After extensive renovation, it reopened in 562 A.D. to the delight of Justinian, who, three years before his death, saw his great church survive one of nature’s worst calamities.

On May 29, 1453, Mehmed II and his army entered the city, immediately marching on Hagia Sophia. In their book Strolling Through Istanbul, John Freely and Hilary Sumner-Boyd describe how Mehmed “dismounted at the door of the church and bent down to take a handful of earth, which he then sprinkled over his turban as an act of humility before God.”

In the five centuries following that symbolic act, the greatest religious building of the Ottoman Empire continued to shine—but this time, the glory belonged to Islam. Hagia Sophia became an imperial mosque; it came to boast four minarets (these also serve an architectural purpose, protecting the building against collapsing onto itself) and additional türbes (Islamic mausoleums).

Centuries later, in 1935, its role changed again. Twelve years after the foundation of the Turkish republic, President Mustafa Kemal Atatürk signed a decision that turned Hagia Sophia into a secular museum. According to the Encyclopedia of the Ottoman Empire, Atatürk’s decision not only turned Hagia Sophia into “an artifact of the past” but rendered it “a site of memory instead of … a symbol of lived religious experience.” In the decades to come, the secularized building would serve as Istanbul’s main tourist attraction; in 2012 alone it attracted around three and a half million visitors.

Today, the building is on the brink of another transformation; 2014 may be remembered as the year that decided Hagia Sophia’s fate. Last month, Yusuf Halaçoğlu, a parliamentarian from the nationalist MHP party, filed a proposal founded on a curious historical argument that brings to mind the books of Dan Brown and Umberto Eco. According to Halaçoğlu, the 1935 decree that transformed Hagia Sophia into a museum was forged. Atatürk, he argued, had never wanted the building to be a museum, and thanks to a legal loophole, the current parliament could easily transform the museum back into a mosque.

Was it conceivable that a forgery could be at the heart of arguably the most significant decision in Turkey’s early republican history? Halaçoğlu’s argument hinged on Atatürk’s name. Before the parliament had christened him Atatürk (“the father of Turks”) on November 27, 1934, he’d been known simply as Mustafa Kemal. Only after the Turkish parliament retitled him did he start to sign documents under the new name. But the motion that desanctified Hagia Sophia was passed on November 24, and it was signed “K. Atatürk”—three days too soon, to Halaçoğlu’s mind.

Further complicating matters, the decree’s issue number was 1589, while another decree issued two days earlier was numbered 1606. Halaçoğlu also pointed out that the decree was never published in the Official Gazette (Resmi Gazete) of the Republic, which may signal that the decree had been added to the presidential archive at a later date.

To prove his theory, Halaçoğlu brought the decree document and Mustafa Kemal Atatürk’s signature to the Police Headquarters of Turkey and asked experts to compare the two; there does indeed seem to be a difference between them. The experts said as much, but not everyone was convinced—intellectuals and historians began to weigh in. In Yeni Akit, Turkey’s most conservative newspaper, well known for its opposition to republican reforms, Faruk Köse argued that the forgery theory was an absurd attempt to distance Atatürk from the cultural revolutions of early twentieth century. A forgery was impossible, Köse said. The mosque was turned into a museum in 1935 and opened its doors on February 1 of that year; since Atatürk died on November 10, 1938, how on earth could he not have known about the transformation of the greatest mosque of Islam into a museum? As for the experts’ verdict about the difference in signatures, Köse argued that it was natural for a person using a new signature for the first time to make slight alterations to it later. He also claimed that Atatürk would’ve executed anyone who attempted to forge his signature—so absolute was his authority.

One morning not long ago, I took a tram to Hagia Sophia with my girlfriend. I wanted to get at the heart of the controversy. The entrance fee is twenty-five liras, which visitors are allowed to pay only after standing in a very long queue where guides of varying degrees of competence vie for attention.

We entered the museum through the impressive Imperial Door, which only the emperors could use in the Byzantine era. Once inside, the first thing that struck us was the coldness of the place—the chill almost overshadowed the beauty of the grand dome, which is 108 feet in diameter, rising to 180 feet above the floor. Having watched a National Geographic documentary about its construction the night before, we had our doubts about the building’s safety.

More than anything else, the interior of the museum resembles an endless construction site. The library in the south aisle, commissioned by Sultan Mahmud in the eighteenth century, is currently being renovated, and a huge scaffold stands at the center with warning signs placed on columns around it. My girlfriend remembered having visited in 2010—she said the scaffolding had been removed then. I found that difficult to believe, but she said she could prove it with pictures.

Before climbing upstairs, we looked at the circular calligraphy panels that hang from the piers. Painted by Kazasker Mustafa Izzet Efendi, they contain the names of Allah, the prophet Muhammad, his four caliphs (Abu Bakr, Umar, Uthman, and Ali), and Muhammad’s grandchildren Hussein and Hassan. They stand in striking contrast with the Christian imagery of the mosaics: the cohabitation of Islamic words and Christian images is a beautiful thing to behold.

There are more than a hundred columns in the building, but none is more interesting than the so-called sweating column on the northern corner. Brought from the Temple of Artemis, the column has a huge hole in its center where visitors can insert their thumbs and rotate their hands, thus transmitting their dreams to the ancient structure’s wish-fulfillment center. Because water can be seen coming out of it, people believe the column sweats, or cries, and that this is a miracle—it may also be a sign of poor care.

We walked among crowds of tourists, tour guides, and security guards, seeking perhaps the most curious object in the museum—not an inanimate piece of ancient history but a living animal. Gri, the famous Hagia Sophia cat, has a Tumblr devoted to him; the cross-eyed creature was named after the color of his coat. When Barack Obama visited Hagia Sophia in 2009, he was photographed fondling Gri’s head. We, too, fondled it; I asked Gri about his take on the mosque-versus-museum controversy. He raised his tail, purred, and turned away.

Not everyone’s reactions are so docile. “We are looking at a sad Hagia Sophia, but hopefully we will see it smiling again soon,” said the Turkish deputy prime minister last year, implying that it should be opened to Islamic service. According to the Greek Foreign Ministry, his suggestion had been “an insult to the religious sensibilities of millions of Christians and actions that are anachronistic and incomprehensible from a state that declares it wants to participate as a full member in the EU.” Ecumenical Patriarch Bartholomew was quoted as saying, “If it is to reopen as a house of worship, then it should open as a Christian church.”

Although most people take an either/or stance, some have proposed opening Hagia Sophia to both Islamic and Christian services. This is a welcome prospect to Christians, who have made a number of attempts to organize religious rituals. On one such occasion, in 2010, Turkey’s director of religious affairs said, “Turkey would not be a Christian country just because Christians performed their religious duties in a few churches.”

There’s precedent for such a hybrid, too. I came across numerous articles about the so-called church-mosques of Anatolia. Pazaryeri Camii, in the coastal city of Izmir, is one example: built for Christian service in 1874, it was repurposed as a mosque once Turkey became a republic. During the building’s renovation, the experts found Christian icons and decided to install a curtain system to cover them during Islamic prayers. Another church-mosque, in the Çardak village of Göreme, has been used by both Orthodox Christians and Muslims. Indeed, a Turkish columnist recommended a similar solution for Hagia Sophia: “We should allow Aya Sofya to become all three things at the same time!” she wrote. “Let’s keep it as a museum from Monday to Thursday, turn it into a mosque on Friday, close it for holiday on Saturday and use it as a church on Sunday. We can cover the floor with a carpet on Thursday nights and place chairs on Saturday nights.”

Whichever outcome arrives, it would be great if someone installed proper heating equipment there. And whoever manages the building shouldn’t forget about feeding Gri and managing his Tumblr feed. Above all, respect for the building’s immense heritage is a must. Otherwise the ghosts of Justinian and Constantine will surely haunt us—and so will the ghost of Mehmed the Conqueror, whose first action in front of Hagia Sophia was one of humility.

Kaya Genç is a novelist and essayist from Istanbul.