Vatican City is the smallest country in the world and a European microstate enclaved by Italy, similar to San Marino.
Monaco is the second-smallest country in the world and a European microstate located on the French Riviera, similar to San Marino in being a popular tourist destination and having a high GDP per capita.
Liechtenstein is the fourth-smallest country in the world and a European microstate situated between Switzerland and Austria, similar to San Marino in being a constitutional monarchy and having a low tax regime.
Andorra is the sixth-smallest country in the world and a European microstate located in the Pyrenees mountains between Spain and France, similar to San Marino in being a co-principality and having a rich cultural heritage.
Malta is the tenth-smallest country in the world and a European microstate located in the Mediterranean Sea, similar to San Marino in being a member of the European Union and having a long history of sovereignty.