Looking on the internet deeply has found these results:

I am in kolkata is the most popular phrase on the web.

I am at kolkata 15,320 results on the web	I am in kolkata 1170,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
I checked the flights this morning, and there's one for Kolkata on Thursday. raised, and London born, Kashmir Because he knew I had moved to Kolkata after my wedding. Raqib Shaw is Kolkata K7 49 to Kolkata, please proceed to gate B42. But I told you, I have to be in Kolkata tomorrow. I'm going to Kolkata for three days.	not for India, but for Kolkata. I checked the flights this morning, and there's one for Kolkata on Thursday. We'd all seen matches in Kolkata, but we'd never seen anything like this: Shah Rukh, with the Bengali song, getting the audiences all worked up for Kolkata But I told you, I have to be in Kolkata tomorrow. An Indian film star hugging a Pakistani cricketer because they'd won in Kolkata. I'm going to Kolkata for three days. We'd all seen matches in Kolkata, but we'd never seen anything like this: Because he knew I had moved to Kolkata after my wedding.

I am at kolkata

15,320 results on the web

I am in kolkata

1170,000 results on the web

More popular!

not for India, but for Kolkata.
I checked the flights this morning, and there's one for Kolkata on Thursday.
We'd all seen matches in Kolkata, but we'd never seen anything like this: Shah Rukh, with the Bengali song, getting the audiences all worked up for Kolkata
But I told you, I have to be in Kolkata tomorrow.
An Indian film star hugging a Pakistani cricketer because they'd won in Kolkata.
I'm going to Kolkata for three days.
We'd all seen matches in Kolkata, but we'd never seen anything like this:
Because he knew I had moved to Kolkata after my wedding.