1. Tokyo, Japan

Population in 2016: 38,140,000

As of 2016, Tokyo is the most populated city on Earth. Known for its modern design, dedication to cutting-edge technology, and crowded streets, Tokyo has long had a reputation of being densely populated.

While the UN still expects Tokyo to hold the number one spot in terms of population in 2030, the city's population is expected to decline to 37,190,000 over the next 13 years.