When usually one reaches one's office, walks into it-

" I arrived at the office"
" I arrived in the office"

Do both of these make sense?

Yes. The one you choose would depend on the context

Yes. The one you choose would depend on the context

When usually one reaches one's office, walks into it

I don't know what else I should explain, I am just asking in general. This is the context here.
A person who simply goes to his office daily and when he reaches, How would you say it ?
Using At or in?

We typically say “at the office” when we are referring to a place of work where everyone is an office worker. We typically say “in the office” when we are referring to a particular office, which may be situated in a building where there are non-office activities. These are not hard and fast rules, just typical usages.

We typically say “at the office” when we are referring to a place of work where everyone is an office worker. We typically say “in the office” when we are referring to a particular office, which may be situated in a building where there are non-office activities. These are not hard and fast rules, just typical usages.

This is an very interesting question for English learners in China. People almost in every non-international school students are taught that they use "in" before a bigger place like a city and 'at" before a smaller place like "school" or "hospital".

We typically say “at the office” when we are referring to a place of work where everyone is an office worker. We typically say “in the office” when we are referring to a particular office, which may be situated in a building where there are non-office activities. These are not hard and fast rules, just typical usages.

But my question is not about whether we should use "at" or "in" with office when you are working there.
My question is when we reach there what should we use.

Please read my reply more carefully