Learn Polish: Często spędzamy weekendy w europejskich stolicach. - We often spend weekends in European capitals.

It is in the locative plural case because it follows the preposition w (in) to describe a location. The great news about the locative plural is that it is very regular: almost all nouns, regardless of their gender, take the ending -ach. So, stolica (capital) becomes stolicach.

How do adjectives work in the locative plural, like in europejskich?

In the locative plural, adjectives take either the ending -ich or -ych. Because the base adjective europejski has a k before the final vowel, it takes the softer -ich ending. This makes it europejskich to properly match the locative plural noun stolicach.

Why is the word weekendy not in the locative case too?

Even though it is plural, weekendy is the direct object of the verb spędzamy (we spend). Direct objects take the accusative case, not the locative. For inanimate masculine nouns like weekend, the accusative plural is the exact same as the basic nominative plural, which ends in -y.

Why do we use the verb spędzamy instead of the perfective spędzimy?