1. Singapore: Singapore is an island city-state located off the southern tip of the Malay Peninsula. It has a population of around 5.8 million people and a highly developed economy. Singapore is known for its modern infrastructure, financial services, and tourism industry.
2. Monaco: Monaco is a city-state located on the French Riviera. It has a population of around 39,000 people and is known for its glamorous lifestyle, casinos, and luxury tourism. Monaco is also a major financial center.
3. Vatican City: Vatican City is a city-state located within Rome, Italy. It is the seat of the Roman Catholic Church and has a population of around 800 people. Vatican City is considered a sovereign entity under international law and has its own government and currency.
4. San Marino: San Marino is a city-state located in the Apennine Mountains of central Italy. It has a population of around 33,000 people and is known for its medieval architecture, stunning scenery, and historical importance. San Marino has been an independent state since the 13th century.
5. Liechtenstein: Liechtenstein is a city-state located in the Alps between Switzerland and Austria. It has a population of around 38,000 people and is known for its beautiful landscapes, castles, and strong economy. Liechtenstein is a constitutional monarchy and has a long history of neutrality.
These modern city-states have political and economic systems that differ from nation-states, which have larger territories and more diverse populations. They also play significant roles in global politics, economics, and culture. Some other notable examples of modern city-states include Gibraltar, Andorra, and Malta.