This is the 2795th most frequent Russian word.
петрозаводск
"Petrozavodsk" is the name of a city in northwest Russia.
The word "Петрозаводск" is used as a proper noun and the subject of the sentence.
Петрозаводск - это столица Карелии.
Petrozavodsk is the capital of Karelia.
In this sentence, "Петрозаводск" is utilized as the direct object of the verb посетить (to visit).
Я хочу посетить Петрозаводск следующим летом.
I want to visit Petrozavodsk next summer.
Here, the word "Петрозаводск" is in the prepositional case to indicate the topic being discussed, following the preposition o (about).