I'm afraid it is not correct.
The key parts of the first clause up to ", and" may be simplified as:
- Venice IS a city [across small islands [that are linked by bridges]] HAS PLAYED an important role ...
Reducing it further, we have "Venice IS a city HAS PLAYED ...", which has two predicates (is, has) for one subject.
It is a clear grammatical error.
I suggest you break the sentence into two simple ones.
- Venice is a city in northeastern Italy situated across a group of 118 small islands that are linked by numerous bridges spanning the separating canals. It has played an important role in the history of symphonic and operatic music, including being the birthplace of Antonio Vivaldi. Venice has been ranked the most beautiful city in the world as of 2016 [(alternatively) Venice was ranked the most beautiful city in the world in a 2016 survey].
(I rephrased "separated by canals and linked by bridges", as I found the opposite meanings in sequence a little odd)