Is "We arrived at Delhi yesterday" correct?

Why

Aarav is treating "arrive" as if it always pairs with the same preposition regardless of what follows, which would certainly be simpler. English actually varies this preposition based on the SIZE of the place being arrived at. Large places — cities, countries, wide areas you can move around inside — take "arrive in": "arrive in Delhi", "arrive in India". Small, specific points — a station, an airport gate, a particular building or address — take "arrive at": "arrive at the station", "arrive at the airport". A city is somewhere you arrive INTO, a large space you then move around within; a station is a single specific point you arrive AT. Test: notice "arrive in the classroom" sounds odd compared to "arrive at the classroom" — a classroom is treated as a specific point, not a wide area, so it takes "at" like the station does, following the size of the place rather than any fixed word for "arrive". Yes, his sister is right: "arrived in Delhi" for the large city, and "arrived at the station" for the specific point — different sizes of place take different prepositions after "arrive".