«allo zoo» vs «nello zoo»
In English, "I am at the zoo" could mean that I am inside of the zoo, or I am at its entrance or in its parking lot. But "I am in the zoo" would mean that I am definitely inside it.
Is it similar with
«io sono allo zoo»
«io sono nello zoo»
Or what is the distinction?
«io sono allo zoo» occurs in the duoLingo lessons, but the discussion is merely full of people asking this question about how these two above differ, and no answers.
When talking about public places (hospital, school, zoo, etc.) using "nello/a" would suggest that you are inside the building and you are emphasizing the "building" part. While using "allo/a" would suggest that you are referring to the more abstract meaning that includes the services you can get there etc. For example: "Si trovano nel nuovo ospedale" (They are inside the new hospital = the new building) "Ieri era all'ospedale per una visita" (Yesterday he was at the hospital for a medical examination). Hope this helps a bit.