I've faced with two confusing examples in my English course:
Notice at the restaurant: "Dogs must not be taken to the restaurant"
Notice in a picture gallery: "Cameras, sticks and umbrellas must be left at the desk"
And I can't understand why they used two different prepositions of a place. In both examples, we speak about some kind of place, not some building so we should use 'at' preposition as in the first one.
Can you explain please the main reason?