"Where is the next stop?"
Translation:Dov'è la prossima fermata?
There's no real explanation for it, other than the centuries of evolution of the language: some adjectives go after the noun, some go before, some can be in either place, some change meaning depending on the place, and some change place depending on the noun. You can say "l'anno prossimo" or "il prossimo anno" (next year), but "la prossima volta" (next time), "nei prossimi giorni" (in the next few days), and so on; you can say "giovedì prossimo" (next Thursday) but you must add the article in "il prossimo giovedì". You can only say "prendo il prossimo treno" (I'll take the next train), "guardo il prossimo film" (I'll watch the next movie), or like in this case "scendo alla prossima fermata" (I'll get down at the next stop); it would just be very unnatural otherwise.
Bravo, formica, e grazie mille! Super explanation. So much to learn, but I must remember -- communication is the important goal -- not perfection. The Italians I know are very forgiving and understanding of those of us who try to learn their language. They are only too happy that we are making the effort.