Breakdown of W opuszczonym budynku nikt nie mieszka.
nie
no / not
mieszkać
to live
w
in / on (a day)
budynek
building
Questions & Answers about W opuszczonym budynku nikt nie mieszka.
Wait, doesn't nikt nie mieszka literally mean 'nobody doesn't live'?
Yes, literally it does! But in Polish, double negation is mandatory. This means if you use a negative pronoun like nikt (nobody), you must also put nie in front of the verb. It doesn't cancel out the negative like it does in English.
Why is the word for building budynku instead of budynek?
Because of the preposition w (in). When w is used to show a location, the noun that follows must take the Locative case. Also notice the 'fleeting e' rule in action: the 'e' in budynek drops out when we add the Locative -u ending to make budynku.
What case is opuszczonym in?
It is also in the Locative case, because adjectives must match their nouns. The dictionary form is opuszczony (abandoned). To match the masculine noun budynku, the adjective takes the Locative ending -ym, becoming opuszczonym.
Could I change the word order and say Nikt nie mieszka w opuszczonym budynku?
Absolutely. Polish word order is quite flexible. Putting the location first (W opuszczonym budynku...) simply sets the scene, which is a very common and natural way to start a sentence in Polish. Your version is also perfectly correct.