Learn Croatian: Istražujemo napuštena mjesta gdje stare zgrade propadaju. - We explore abandoned places where old buildings decay.

Here, gdje (where) acts as a relative pronoun instead of a question word. It connects the main clause (Istražujemo napuštena mjesta) to the descriptive clause (stare zgrade propadaju), specifically referring back to a physical location.

Could I use a different relative pronoun instead of gdje here?

Yes! You could say u kojima (in which). However, when talking about physical spaces like mjesta (places), Croatian speakers frequently use gdje because it is much simpler than matching the case, gender, and number required by the pronoun koji.

What case is napuštena mjesta in, and why do both words end in -a?

It is in the accusative case because it is the direct object of the verb istražujemo (we explore). The noun mjesto (place) is neuter. For neuter nouns, the plural nominative and accusative forms are identical and end in -a. The adjective napuštena takes the same ending to match.

The word napuštena looks a bit like a verb but is used as an adjective here. How does that work?

It is a passive adjective (also called a passive participle) formed from the verb napustiti (to leave or abandon). When used this way, it translates to "abandoned" and takes regular adjective endings to match the noun it describes.