This is the 3270th most frequent German word.
freiburg
"Freiburg" is a German city name, meaning "free town" or "fortified town."
Here, 'Freiburg' is used as a noun representing the city in Germany, specifically referring to a place.
Ich habe letztes Jahr Freiburg besucht.
I visited Freiburg last year.
In this sentence, 'Freiburger' functions as an adjective derived from the proper noun 'Freiburg,' describing something that originates from Freiburg, namely the Münster (Cathedral).
Das Freiburger Münster ist über 700 Jahre alt.
The Freiburg Cathedral is over 700 years old.
Here, 'Freiburg' again serves as a noun, specifically part of a name, representing an institution located within the city of Freiburg.