From 7000 BCE to today, at least 19 cities have led the world in population.

Here’s the abridged version of this fascinating chain:

Çatalhöyük led the world with 1,000 people by 7000 BCE.

Tell Brak led the world with 4,000 people by 5000 BCE.

Uruk took the lead with 40,000 people by 3300 BCE.

Memphis took the lead with 35,000 people by 2250 BCE.

Babylon took the lead with 60,000 people in 1770 BCE.

Thebes took the lead with 75,000 people by 1500 BCE.

Nimrud took the lead with 75,000 people by 800 BCE.

Nineveh took the lead with 100,000 people by 700 BCE.

Alexandria took the lead with 150,000 people by 300 BCE.

Rome took the lead with 400,000 people by 100 BCE.

Constantinople led with world with 450,000 people by 500 CE.

Chang’an took the lead with 600,000 people by 600 CE.

Kaifeng took the lead with 1M people by 1000 CE.

Hangzhou took the lead with 1M people by 1200 CE.

Nanjing took the lead with 500,000 people by 1400 CE.

Beijing took the lead with 600,000 people by 1450 CE.

London took the lead with 1.9 million people by 1841.

New York took the lead with 7.8 million people by 1925.

Tokyo took the lead with 15 million people by 1965.

The details are spelled out at this source: The 19 greatest cities in history – Business Insider