This is the 7992nd most frequent Russian word.
копенгагена
"Копенгагена" is the genitive case of "Копенгаген," meaning "of Copenhagen," referring to the capital of Denmark.
Here, "Копенгагена" is used as a proper noun denoting the city of Copenhagen in the genitive case, indicating possession (the center of Copenhagen).
Мы посетили исторический центр Копенгагена во время нашего путешествия.
We visited the historical center of Copenhagen during our trip.
In this context, "Копенгагена" conveys the genitive case form to show a relationship to the city's culture.
Я слышал много интересного о культуре Копенгагена.
I have heard many interesting things about the culture of Copenhagen.
This usage again employs "Копенгагена" in the genitive case to indicate the descriptive linkage to 'streets'.