What is Istanbul Known As? Names, Money and Why It Matters

Ask a hundred people what Istanbul is known as and you will get a hundred slightly different answers. Some will reach for the old names: Constantinople, Byzantium, the city the Ottomans called Kostantiniyye. Others will tell you it is the money capital of Turkey, the place where almost a third of the country’s economy happens. And plenty will just say it is one of the most beautiful cities they have ever set foot in. They are all correct, which is exactly what makes the question fun to answer.

So here is the short version up front. Istanbul is known as three big things: its historical names (Constantinople above all), the economic heart of Turkey, and a genuinely world-class city to visit. Below I will take each one in turn, with the real history and a few numbers that surprised even me when I looked them up.

• 1. What is Istanbul known as? Constantinople
• 2. The economic center of Turkey
• 3. One of the world’s great cities to visit
• What is Istanbul known as? Final words

1. What is Istanbul Known As? Constantinople

If there is one historical name that still follows the city around, it is Constantinople. You hear it in songs, in films, in the way older travelers talk about the place. Even though the official name became Istanbul in the early years of the Republic, a lot of people still know it, instinctively, as Constantinople. If that gap between the two names interests you, I wrote a whole piece on why Istanbul is not Constantinople anymore that goes deeper than I can here.

The reason the name stuck is simple: it was the city’s name for an extraordinarily long time. In 324 the Roman emperor Constantine the Great chose this spot as his new capital, and on 11 May 330 it was formally dedicated as Constantinople, “the city of Constantine.” It kept that name through more than a thousand years of Byzantine rule. When the Ottomans took the city in 1453, they did not erase the name either. They used Kostantiniyye, an Arabized form of Constantinople, in thousands of official documents right up to the 20th century. So for the better part of 1,600 years, in one form or another, this was Constantine’s city. Names like that do not fade in a generation.

What Are the Other Old Names of Istanbul?

Constantinople is the famous one, but it is far from the first. Long before Constantine, Greek colonists from Megara founded a settlement here around 660 BC and called it Byzantion, or Byzantium in Latin. Legend credits a king named Byzas as the founder, which is where the name comes from. Byzantium is so well known that the entire Eastern Roman Empire is now remembered as the Byzantine Empire, even though the people living in it simply called themselves Romans.

Go back even further and you reach the murkiest name of all. According to Pliny the Elder, the earliest settlement on this peninsula, near today’s Sarayburnu, was called Lygos, a Thracian village that may date back to the 13th to 11th centuries BC. If you want the full timeline from that first village onward, the post on Istanbul before it became Constantinople is the one I would send you to.

The Ottoman centuries added their own names, too. Alongside Kostantiniyye, the city was known by poetic and administrative titles such as Payitaht (the seat of the throne), Deraliye, Asitane, and Islambol. The word Istanbul itself comes from the Greek phrase “eis tin Polin,” meaning “to the City,” which is a lovely detail: for centuries this was so obviously The City that you did not even need to name it. It was made the sole official name in 1930.

Why Is Istanbul Also Known As Constantinople?

This question comes up a lot, so it deserves a direct answer. Istanbul is still known as Constantinople by some people because that name carried such weight, for such a long time, across so many cultures. The Byzantines themselves did not even bother with the formal name half the time. They called it Basilis ton poleon, the “Queen of Cities,” because in the medieval world it really was the richest and most important city most people could imagine. Travelers wrote home about it the way people write about a place that does not seem quite real.

That reputation outlived the empire. Centuries later Napoleon is supposed to have said that if the world were a single country, its capital would be Constantinople, a line that captures exactly why the name refuses to die. It is shorthand for a city that sat at the crossroads of Europe and Asia and controlled the Bosphorus for well over a thousand years. So when someone calls Istanbul “Constantinople” today, they are usually not being pedantic. They are reaching for all of that history in a single word. If the layered past of the place pulls at you, the deep dive into Istanbul’s history and how this city kept reinventing itself is worth your time.

2. The Economic Center of Turkey

Beyond the old names, the second thing Istanbul is famously known as is the economic engine of Turkey, and here the numbers do the talking. This is by far the country’s largest city. As of the most recent counts, Istanbul’s population sits at roughly 15.8 million people, which means more people live in this one city than in many entire European countries.

The economic concentration is even more striking than the population. In 2024 Istanbul produced around 305 billion US dollars of output, which was about 29 percent of Turkey’s entire GDP. Almost a third of the national economy happens in a single province. The city accounts for the lion’s share of the country’s finance and insurance activity (close to 60 percent) and its information and communication sector (around 64 percent), plus a big chunk of industrial output and tax revenue. When people say Istanbul carries the country financially, they are not exaggerating.

A lot of this comes down to geography, the same geography that made it valuable two thousand years ago. The city sits astride the strait connecting the Black Sea to the Mediterranean, with one foot in Europe and one in Asia, which has made it a trade hub since antiquity. That was true under the Byzantines, true under the Ottomans, and it is true now. Interestingly, Istanbul is not even the capital: that role went to Ankara when the Republic was founded, a decision I unpack in why Ankara, not Istanbul, became the capital. The capital moved, but the money stayed put.

3. One of the World’s Great Cities to Visit

The third answer is the one I care about most, because it is the reason this blog exists. Istanbul is known, simply, as one of the best cities on earth to visit. The history and the economics are real, but for a traveler the appeal is the texture of the place: thousand-year-old monuments a tram ride from rooftop bars, ferries crossing the Bosphorus at sunset, the smell of grilling fish near the Galata Bridge, cats lounging on every other doorstep.

There is genuinely too much to do, which is a good problem to have. You can spend a morning inside Hagia Sophia, a museum-mosque that has watched the city change names more than once, then cross to the Asian side for the markets of Kadikoy by afternoon. You can swim off the Princes’ Islands in summer, hunt for the best baklava, or just walk. If you are mapping out a first trip, my three-day Istanbul itinerary covers the classic route without overloading you, and the rundown of why so many travelers fall for Istanbul explains the pull better than a checklist ever could. For the headline sights, the guide to Istanbul’s most famous landmarks is a solid place to start.

That side of the city is no secret, of course. Istanbul regularly ranks among the most visited cities in the world, and once you have been, it is easy to see why people keep coming back.

What is Istanbul Known As? Final Words

So, what is Istanbul known as? Three things, really, and they all feed into each other. It is known by its old names, above all Byzantium and Constantinople, names that still carry the weight of nearly two millennia of history. It is known as the economic heart of Turkey, a single city responsible for close to a third of the national economy. And it is known as a wonderful place to visit, a city that somehow stays exciting no matter how many times you go back.

My honest take is that the names and the numbers are just the setup. The real answer to “what is Istanbul known as” is the feeling you get standing on a ferry deck with the old city on one side and the new on the other, realizing that every empire that ever wanted this view felt exactly the same way. That is the part no statistic captures, and the part that keeps the city famous.