Anyone who has ever sat in one of Istanbul’s endless traffic jams, listening to a taxi driver blast his horn and curse the son-of-a-donkey unloading a moving van in front of him, will agree that the city’s transportation system leaves much to be desired. City planners meant to solve this problem when they began construction of a $4 billion subway tunnel beneath the Bosporus. Then, to the planners’ horror, the project’s engineers discovered the lost Byzantine port of Theodosius. Known to archaeologists only from ancient texts, the port had been sleeping peacefully since the fourth century ad—directly underneath the site of the proposed main transit station in Yenikapı.

The tunnel-digging halted, entailing untold millions in economic losses, and the artifact-digging began. An army of archaeologists descended upon the pit, working around the clock to preserve the ancient jetties and docks, while Istanbul’s traffic grew yet more snarled. Newspapers reported that Metin Gokcay, the dig’s chief archaeologist, was “rejecting all talk of deadlines.” It’s not difficult to imagine the hand-wringing that those words must have prompted among budget planners.

The planners no doubt considered throwing themselves into the Bosporus when the excavation then unearthed something even better—or worse, depending on your perspective—underneath those remains: 8,000-year-old human clothes, urns, ashes, and utensils. These artifacts stunned historians and forced them to revisit their understanding of the city’s age and origins. The discovery posed a fresh moral problem, too: excavating the top layer might damage the one above it—or vice versa. So the decision was no longer, “Should we conserve these remains?” It was, “Which remains should we conserve?”

The subway project, originally scheduled to be finished in May 2010, is now at least six years behind schedule. The route has been changed 11 times in response to new findings, driving everyone concerned to the brink of madness. The government is desperate to finish the project but well aware that the world is watching. No one wants to be known to future generations as the destroyer of 8,000 years’ worth of civilization.

Decisions like this are made on a smaller scale every day in every neighborhood of Istanbul. Istanbul’s population—by some estimates, as high as 20 million—has more than tripled since 1980, enlarged by decades of migration from Turkey’s poor rural regions. The city desperately needs better roads, subways, and housing. Its infrastructure is archaic, a problem illustrated in 2009 when flash floods gushed across the city’s arterial roads, killing scores. The catastrophe was widely ascribed to inadequate infrastructure, shoddy construction, and poor urban planning.

But building the city’s future will assuredly destroy its past. Thriving human settlements existed here thousands of years before the Roman, Byzantine, and Ottoman Empires. If you look under the ground around Istanbul’s Golden Horn, it’s almost impossible not to find something archaeologically significant. Developers covet these sites today for precisely the geographic features—for example, natural ports—that made them equally desirable long ago. The more economically attractive the location, the more likely it is to have significant remains, and the more likely it is that someone will have an economic motivation to make those remains disappear.

Government-backed developers, for example, were determined to expand the Four Seasons Hotel in Sultanhamet, even though it sat atop relics from the Palatium Magnum built by Emperor Constantine I in the fourth century ad. Dogged local investigative journalism and the threat of international opprobrium put a halt to those plans. On the other side of the Golden Horn, when it became obvious that the construction of the Swiss and the Conrad Hotels in Beşiktaş would destroy significant archaeological artifacts, the local government objected, pointing to Turkey’s laws on historic preservation. The developers went over their heads to Ankara and appealed to the laws on promoting tourism. Parliament decided that Turkey needed foreign direct investment, and the tourism laws prevailed. There was an irony in the decision, of course: Istanbul’s heritage is precisely what attracts tourists. Then again, if there are no hotels, there’s nowhere for tourists to stay.

There is no way to resolve the tension between letting this megacity develop economically and protecting its priceless archaeological treasures. Obviously, you can’t turn an entire city into a museum where no new construction is allowed. According to some archaeologists, that’s exactly what you’d have to do to protect Turkish historic artifacts—leave them all in the ground, untouched, since even careful excavation might destroy them. But Turkey is not a wealthy country. It’s hard to feel morally confident in saying that Turkish citizens need Neolithic hairbrushes more than they need houses, factories, ports, dams, mines, and roads—especially when they’re dying in flash floods.

So something has to be destroyed. But who decides which part of the city’s past is most important? Legally, Turkey’s monument board has the authority to decide what to save: in principle, if more than 60 percent of a neighborhood is more than 100 years old, it cannot be touched without the board’s permission. The board deals daily with a massive number of requests and decisions, but it has neither the time nor the resources to ensure that its decisions are upheld. For example, it reviews all plans for development in sensitive areas. The plans then get sent to municipal government offices for approval—but often, the plans submitted to the board are different from the ones that go to the local government, and the board is none the wiser.

Further, the process of evaluating a preservation claim is often slow and bureaucratic. Sara Nur Yildiz, a historian at Istanbul’s Bilgi University, recalls noticing a distinctive earthen mound at the edge of a construction site in her upscale neighborhood in Cihangir. She suspected immediately that it was an archaeologically significant well. “I told them to stop digging,” she says, “but they ignored me.” She filed a petition with the monument board. Ultimately, the board agreed with her and halted the construction. But by the time the board finished studying the case and relaying its verdict to the workers, half of the structure had been demolished.

In general, Ottoman Empire relics fare better than Byzantine ruins. In the minds of certain officials, the latter sound a bit too much like Greek ruins, which aren’t, after all, part of their history. Archaeologists associated with TAY—the Archaeological Settlements of Turkey Project—have compiled inventories of priceless endangered sites. They report a “persistent and intense threat” to Byzantine remains throughout the city from the construction of roads and modern housing. The Edirnekapı and Topkapı sections of the historic city walls, they lament, vanished during the construction of Adnan Menderes Boulevard and Millet Street. Another problem: there is “almost no coordination,” say archaeologists with TAY, between the government departments charged with preserving cultural heritage and those responsible for public works.

Many academics have worked to draw up conservation plans for the city. So has UNESCO. But they don’t have the power to enforce them. UNESCO, claiming that the Turkish government has disregarded its reports, has threatened to embarrass Istanbul by putting its cultural treasures on its endangered list. But on the historic peninsula, rates of return on investment in development are among the highest in the world—exceeded only by those in Moscow. For developers, the amount of money at stake is phantasmagoric. They’re willing to spend a lot to make legal and political obstacles go away. Archaeologists can’t compete.

So come visit now, while it’s all still here.

Claire Berlinski, a City Journal contributing editor, is an American journalist who lives in Istanbul.