I'm from the US, and there are many beautiful cities here but my favorite is Boston. It's beautiful, clean, near the ocean, many different things to do, and many different people to meet. :) It's full of interesting historical things, and lots of fun places to shop, eat or play. 

I'm from the US, but some of the most beautiful cities here would be New York City, New York; San Diego, California; Austin, Texas; y Aspen, Colorado! 

I'm from Italy and it's hard to say what cities of my country are the best, in my opinion.

I must mention:

- Rome, "The Great Beauty", is always so magic. It has many problems, like any other city in the world, but it surprises me every time.

- Milan, the financial and industrial centre of Italy, offers a lot of possibilities. The urban style coexists with different types of art, especially in the hidden corners.

- Florence... it's impossible to explain. Maybe this song could describe some of its aspects: https://youtu.be/7mPFOvHa0E4?list=PL84C348A03368BDE3.

- Venice and Verona! They are two of the most famous Italian cities. Their history is so fascinating, too.

- The Cinque Terre and their characteristic landscape...

There are also beautiful or little-known cities like Polignano a Mare, seaside town and birthplace of Domenico Modugno, who sang Nel Blu Dipinto Di Blu (Volare); Taormina, near the Europe's most active volcano, Mount Etna; Bergamo; Trieste; Capri... ok, stop, I colud go on and on :P.

I am from Poland and for me te one of the most beautiful cities is without a doubt Cracow.

This city is famous for its bohemian atmosphere, great theatres, galleries and museums, fantastic cafes, pubs and restaurants where you can spend time with friends. In Cracow you will not get bored!

In Colombia, Medellín. Is the most beautiful in our country, also people here are so nice and polite