Tokyo, Japan, is the most populated city in the world with 37.4 million inhabitants.
Source: World City Populations Review
The narrow street of Harajuku is a colorful shopping hub known for its locals dressing up as Harajuku girls.
Source: TimeOut
At a single time, up to 1,000 people can be seen crossing the street at Shibuya Station.
Source: Go Tokyo
Delhi, India, squeezes 28.5 million people in the city spanning 573 square miles.
Source: World City Populations Review
The main street in Old Delhi used to be a promenade for royals dating back to the 17th century. Today it is one of the most crowded marketplaces with wall-to-wall vendors selling everything from spices to wedding attire.
Source: TripSavy
There are 154 skyscrapers — buildings taller than 150 meters, or 492 feet — in Shanghai. In 2017, China completed building 76 skyscrapers.
Source: The Skyscraper Center, Forbes
The second-largest city in China is Beijing with 19.6 million inhabitants.
Source: World City Populations Review
The traffic in Beijing is so congested, the government limits who can drive on certain days and regulates the law with designated license plates.
Source: Trip Savvy, New York Times
The Chinese New Year celebration in Beijing is a spectacle, but the crowds are so large the holiday is also referred to as the world's "largest human migration."
Source: Trip Savvy, Forbes
The most populated city in Mexico is Mexico City with 21.5 million residents.
Source: World City Populations Review
The metro stations in Mexico City are some of the most crowded transportation systems globally, ranking as the eighth busiest metro in the world and the second-largest rapid transit system in North America.
Source: Railway Technology
More than 20 million people call Cairo, Egypt, home. With high tourist rates, the city is teeming with people.
Source: World City Populations Review
With a rich history, the city attracts several million tourists per year. In 2017, Cairo hosted 8.3 million visitors.
Source: Egypt Today
Mumbai is the second largest city in India with just under 20 million people.
Source: World City Populations Review
It is estimated that 7.5 million people use commuter trains daily in Mumbai. The overcrowding on the rail system has caused nearly 38,000 deaths since 2007, CNN reported. That's an average of nine deaths per day.
Source: CNN
Dhaka is the largest city and most densely populated in Bangladesh. More than 19.5 million people reside in a total area of 300 kilometers — about 186 miles.
That's 23,234 people per square kilometer, which is just over half a square mile.
Source: World Population Review
To compare, New York City has more than 8 million residents, about 27,000 per square mile.
Source: World City Populations Review, NYC
Buenos Aires, Argentina, is home to nearly 15 million people in just 78 square miles.
Source: World City Populations Review
The Sunday San Telmo market is a major attraction for locals and tourists. Huge crowds are drawn to the 270-stall open air market.
Source: Welcome Argentina
Istanbul is the most populated city in Turkey with 14.7 million people. In 2017, an estimated 7 million foreign tourists visited Istanbul.
Source: World City Populations Review, Daily Sabah
The Hagia Sophia, a former Greek Orthodox Church turned museum, is the most popular tourist destination in Istanbul attracting nearly 3.5 million people annually.
Source: Los Angeles Times
Nigeria is the most populated country in Africa with more than 181 million people. Lagos is the largest city in Nigeria and is home to 13.4 million residents.
Source: WorldAtlas, World City Populations Review
The oldest part of the city, Lagos Island, is connected by bridges to the mainland and home to the Jankara market and Balogun street market where stalls sell anything from linens to lipstick. In the past two decades, vendors have pushed out international banks, airline companies, and real-estate firms in the area, viewed as a "reverse-gentrification" push.
Source: NPR, The Culture Trip
Rio De Janeiro, Brazil, is home to 13.2 million residents. During the 2016 Olympics, more than 490,000 people attended daily games.
Source: World City Populations Review, Olympic
While Brazil prepared for the Rio games, 825 families were forced to relocate to neighboring cities built by the government. The city saw up to 2,000 families relocate in preparation for the Olympic games since 2009.
Source: Los Angeles Times
Russia is the largest country in the world and its capital, Moscow, is the most populated city with 12.4 million residents.
Source: WorldAtlas, World City Populations Review
The 2018 FIFA World Cup drew tremendous crowds to Moscow. An estimated 2.5 million people went to the FIFA Fan Fest.
Source: FIFA
But the crowds made it difficult to enjoy the views in the Red Square and Saint Basil's Cathedral.
Source: FIFA
Just under 11 million people call Paris, France, home. In 2016, the city saw an estimated 36.5 million visitors.
Source: World City Populations Review, USA Today
The most popular tourist attraction is undoubtedly the Eiffel Tour where visitors wait up to three hours to climb to the top.
Source: Trip Advisor
A day away at the Chateau de Versailles isn't any less crowded. The famous Hall of Mirrors will mostly reflect cameras.
Source: Trip Advisor
Indonesia's capital city of Jakarta is the largest city in the country with 10.5 million residents.
Source: World City Populations Review
The Old Town square is a popular tourist spot but many travel websites recommend arriving early to avoid the mass crowds.
Source: Trip Advisor
Bangkok, Thailand, holds more than 10 million residents in 606 square miles. The city is home to 13% of the country's population.
The city has more than 150,000 taxis, any of which can take tourists to and from the Train Night Market.
Source: The Bangkok Shopping Guide
Fans of the "Hangover" movies can even do a tour of every site filmed in the second movie, including the bustling Soi Cowboy street lined with go-go bars.
Source: Klook
South Korea's most populated city is Seoul with just under 10 million people calling the capital home.
Source: World City Populations Review
There are over 124,000 new cars registered in South Korea monthly, according to Trading Economics. The Gangnam district in Seoul is known for having limited parking space due to the amount of cars on the road.
Source: Trading Economics, Business Insider
More than 9 million people live in London, England. In 2017, a record 19 million tourists visited the city.
With 10 million more visitors than residents, the popular tourist destinations like Trafalgar Square, Piccadilly or Oxford Circus, and Buckingham Palace will have the biggest crowds.
Toronto, Canada, is the fourth-largest city in North America with 6 million inhabitants.
Source: World City Populations Review
Downtown Toronto is a tourist's dream. There is the Ripley's Aquarium of Canada, the CN Tower, Steam Whistle Brewing, and the Rogers Center where the Blue Jays play all on the same block — game day crowds are no joke.
Source: Ontario Travel
The largest and most populated city in Spain is Madrid with 6.4 million people calling it home.
Source: World City Populations Review
Traveling to Madrid during Easter is both remarkable and overly crowded. The Semana Santa, or Holy Week, is a weeklong religious observance with parades and prayer.
Source: Go Madrid
Bull fights are famous in Madrid, though tourist attendance isn't as high as local attendance. Today, the Plaza de Toros de Las Ventas arena fits 20,000 spectators.
Source: Trip Savvy, Spain
There are also six weeks out of the year where bull fights happen daily during the San Isidro festival where locals take to the streets and dress up in traditional Madrid costumes.
Source: Trip Savvy, Spain
The FNB soccer stadium is a favorite spot among locals and fits 94,736 spectators. In 2010, the stadium had a record attendance of 94,713.
Source: ESPN
Safari experiences are a major tourist attraction in Johannesburg, but several safari vehicles can be over crowded and with limited window seats — some tourists get stuck cruising in the middle.
Source: Forbes
