Learn Italian: Roma è molto turistica, ma non è la città più turistica. - Rome is very touristy, but it is not the most touristy city.

To say "the most" of something (the relative superlative), Italian uses a definite article like la followed by più and the adjective. Because adjectives usually come after the noun in Italian, the exact order is article (la) + noun (città) + più + adjective (turistica). It literally reads as "the city most touristy."

Why does the adjective take the form turistica here?

It must agree with the noun it describes, which is città. Even though città ends in an accented -à and does not look like a typical feminine word, it is feminine and singular. Therefore, the adjective takes the feminine singular ending -a to become turistica.

Could I leave out the word città at the end of the sentence?

Yes! Because the topic is already established, you can drop the noun the second time. Saying ma non è la più turistica is perfectly natural and translates to "but it is not the most touristy one."

What is the difference between molto turistica and la più turistica?

The phrase molto turistica just means "very touristy" without comparing Rome to anything else. By adding the definite article la in the second half, it becomes a relative superlative. This means you are now comparing Rome to all other cities and talking about "the most" touristy one.