"It is an old prison."
Translation:Es una vieja prisión.
I think you have asked a good question. Not knowing what the speaker meant, it can't be determined. When a descriptive adjective comes before the noun, it has some sort of emotional emphasis to it. In other words, It emphasizes it. In English we might say something like this: It is an old prison (use adjective after the noun). Or, we could say something like this: Wow! it is a really old prison. (in this case adjective before the noun and 'really' isn't translated.) I am told we will eventually get the feeling of which way. I would be happy if I got the feeling now.:]