Rio de Janeiro was founded by Portuguese colonists in 1565.
Guanabara Bay, the second largest bay in Brazil, was one of the main draws.
By 1711, the city had grown.
And it's still one of the most picturesque cities in the world.
New York, as you might have heard, was first called New Amsterdam when it was colonized by Dutch settlers in the early 17th century. It was renamed NYC in 1664 in honor of the Duke of York.
This woodcut of southern Manhattan dates from 1651, when it was still named New Amsterdam.
Between 1870 and 1915, New York's population tripled — surging from 1.5 million to 5 million residents. In this 1900 photo, Italian immigrants crowd the Lower East Side's Mulberry Street.
So the city invested in infrastructure — like the Manhattan Bridge, pictured here in 1909 — to support its burgeoning population.
New York has 8.4 million people living in its five boroughs, according to 2013 census numbers.
Archaeologists say that the first people to settle Paris were the Parisii, a Celtic tribe that set up a settlement on the Seine at around 250 BC.
They settled the Île de la Cité, now the site of Notre Dame.
The Parisii had really sweet coins, like these, which are kept at the Metropolitan Museum of Art.
By the early 1400s, when this painting was made, Paris was already one of Europe's largest cities, if not the largest. That's the Palais de la Cité, a castle on the Île de la Cité, behind the wall.
Now it's one of the most beloved cities on Earth.
Located along the Huangpu River in central Shangai, The Bund neighborhood became a global financial center in the late 1800s, featuring trading houses from the US, Russia, the UK, and Europe.
The Old City of Shanghai — pictured here in the 1880s — came complete with moat.
It was bustling. The commercial success turned a fishing town into the unfortunately named "Pearl of the Orient."
In 1987, the Shanghai district of Pudong was far from developed. It's that marshy area on the other side of the Huangpu River, opposite of the Bund.
In the early 1990s, Pudong opened up to foreign investment.
The area quickly went vertical.
Today, the Bund is one of the most beautiful places in all of China.
And Pudong is one of the most futuristic.
Istanbul (called Byzantium, then Constantinople) was founded in 660 BCE. Constantinople was conquered by the Ottoman Empire in 1453.
The Ottomans quickly transformed the city from a hub of Christianity to a symbol of Islamic culture, building ornate mosques.
Starting in the 19th century, the city expanded northward. Istanbul's commercial center was constructed near the Galata Bridge, which has been re-built five times over the past five centuries.
Istanbul remains the cultural center of Turkey today.
The Romans founded Londinium (now known as London) in 43 AD. You can see the city's first bridge, crossing over the Thames River, in the illustration below.
By the 11th century, London was the largest port in England.
Westminster Abbey, built in the second century, is a World Heritage Site and one of London's oldest and most important buildings. Here it is in a 1749 painting.
In the 17th century, London suffered from the Great Plague, which killed about 100,000 people. In 1666, the Great Fire broke out — It took the city a decade to rebuild.
During the Georgian era (from 1714 to 1830), new districts like Mayfair formed, and new bridges over the Thames encouraged development in South London.
The city continued to rise to the global empire that it is today.
Mexico City, originally named Tenochtitlán, was founded under the Aztec Empire in 1325.
Spanish explorer Hernán Cortés landed there in 1519, and conquered it soon after. Tenochtitlán was renamed "Mexico" in the 15th century, because the Spanish found it easier to pronounce.
Mexico City instituted a grid system (which is how many colonial Spanish cities were set up) starting in the 16th century, with the Zócalo as the main square.
In the late 19th century, the city started developing a modern infrastructure, including roads, schools, and public transport — though many of these resources were concentrated in wealthy areas.
Mexico City grew upwards in the 1950s with the construction of the Torre Latinoamericana — the city's first skyscraper.
Today, Mexico City is a vibrant home to over 8.9 million people.
Moscow was founded in the 12th century. By the 17th century, the Tsars (aka Slavic monarchs including Ivan IV and the Romanovs) were in charge.
The city grew around the Moskva river.
Street vendors set up around the Kremlin.
The world-famous St. Basil's Cathedral was completed in 1561, and it continues to wow visitors with its historic charm...
... while Moscow gets more cutting-edge every year.
The region near today's Johannesburg was originally inhabited by the San people, an indigenous group of hunter-gatherers, roughly 20,000 years ago. In the 13th century, Bantu-speaking people moved to the area, formed small villages, farmed, and mined for iron.
A gold basin, called Witwatersrand, was discovered in 1884, which attracted many Europeans to the area. Today, the basin holds the world's largest known gold reserves and has produced over 1.5 billion ounces of the precious metal.
Around this time, the city was named Johannesburg — though historians don't know exactly why. The city's earliest records, which may have offered information about its etymology, is lost.
By 1900, over 100,000 people lived in Johannesburg.
And today, it is home to over 4.4 million residents, making it the largest city in South Africa.