40. Athens, Greece
> Population density: 13,953 per square mile
> Population: 3,685,000
> Square miles: 264 miles
With a written history going back more than three millennia, Athens is one of the oldest cities in the world. The Greek capital continues to be the heart of the country’s political, cultural, financial and economic life. The ancient city was recently rated highly on a list of cheap European vacations, cited for its antiquities, museums and charming neighborhoods for dining and shopping.
39. Guadalajara, Mexico
> Population density: 15,210 per square mile
> Population: 3,500,000
> Square miles: 230 miles
One of three Mexican cities among the top 50 most densely populated areas in the world, Guadalajara is the capital and the largest urban area in the state of Jalisco. It has gained a reputation as the Silicon Valley of Mexico, with a sizable talent pool of coders, engineers and programmers, along with startups and venture capital. Besides that, Guadalajara is known for its tequila and mariachi bands.
38. Osaka/Kobe/Kyoto, Japan
> Population density: 16,592 per square mile
> Population: 16,425,000
> Square miles: 990 miles
Osaka, Kobe and Kyoto comprise the most densely populated region in Japan; each is the capital of its prefecture, and the combined area is known as the Kansai region. The major industries include manufacturing, distribution, finance and high tech. Attractions such as temples, castles, shopping, and dining abound in the region.
37. Bangkok, Thailand
> Population density: 16,668 per square mile
> Population: 6,500,000
> Square miles: 390 miles
Thailand’s capital as well as its most densely populated city, Bangkok is the country’s center of government, finance and industry. While the majority of the residents are of Thai ethnicity, the city has a variety of districts with Chinese, Indian, Japanese and Arab populations. While numerous sites give Bangkok high marks for quality of life, citing affordable cost of living, vibrant culture, good education and job opportunities. On the down side, its air pollution is among the worst on Earth.
36. Monterrey, Mexico
> Population density: 17,303 per square mile
> Population: 3,200,000
> Square miles: 185 miles
Monterrey is the capital of the Mexican state of Nuevo León, which has the nation’s strongest economy. Construction and manufacturing surged in the state in 2018, and foreign direct investment (FDI) increased 127% over the previous year. The local unemployment rate hovers around 3.5%. But Monterrey isn’t all work and no play — the city currently features a lively nightlife, plus outdoor activities and cultural institutions, and the World Cup is on the schedule for 2024.