Is Stadtpark der, die or das?

The correct German article for Stadtpark is der. The noun Stadtpark is Masculine. So you always say: der Stadtpark. Learn the article together with the noun — German nouns don't follow predictable gender rules most of the time.

The plural of Stadtpark is: die Stadtparks. In the plural, every German noun takes the article "die". So: die Stadtparks. Example: ein Stadtpark → zwei Stadtparks.

Correct: die Stadtparks. The form "die Stadtparks" is wrong. The plural of der Stadtpark is die Stadtparks. In the nominative plural, you always use the article "die".

der Stadtpark follows the four German cases. Nominative: der Stadtpark, Accusative: den Stadtpark, Dative: dem Stadtpark, Genitive: des Stadtparkes. In plural: die Stadtparks / den Stadtparks. Learn these forms together with the noun.

The genitive singular of der Stadtpark is: des Stadtparkes. The genitive plural is der Stadtparks. German uses the genitive to express possession or belonging. Example: die Farbe des Stadtparkes.

The dative plural of Stadtpark is: den Stadtparks. In German, dative plural nouns usually end in "-n". So you say: "mit den Stadtparks". Use this case after prepositions like mit, von, bei, zu.

Stadtpark is a noun and must be capitalized in German. You'll find example sentences above for each case. The article der stays the same in nominative singular but changes in other cases. Practice declension in your own sentences.

Yes, Stadtpark is a noun (also called a substantive). German nouns are always capitalized. The article for Stadtpark is der. Every German noun has a fixed article you must memorize.