Prepositions for “Zoo”

Question

Is there any difference between “at the zoo” and “in the zoo”? I found these examples in the dictionary.

1. We saw a baby polar bear at the zoo.
2. These lions were born in the zoo.
3. ...the penguin pool at London Zoo.

Answer 1

The difference is that the lion lives there, so it is "in" the zoo. The baby polar bear lives in the zoo, too, but when you saw it there, you were "at" the zoo, that is, you don't live there, you were just visiting. The third example could be expressed either way.
Note that preposition usage isn't always hard and fast. It's a subtle usage point.