* "Stayed in" is used to indicate a location where you were residing or spending time *within* that location.
* Example: "I stayed in the hotel room all day." (You were inside the room.)
* "Stayed at" is used to indicate a location where you were residing or spending time, but not necessarily inside the specific location.
* Example: "I stayed at the beach." (You were at the beach, but not necessarily always on the sand itself.)
Here are some examples to illustrate:
* "I stayed in the library" (You were inside the library.)
* "I stayed in London" (You were residing in the city of London.)
* "I stayed at my friend's house" (You were at their house, but not necessarily inside all the time.)
* "I stayed at the airport" (You were in the airport area, but not necessarily in a specific place within it.)
Remember, the best choice depends on the specific situation and what you want to emphasize.