For the item 1 in Part 3 on your Form I-90 application, you have to fill out either the location where you applied for an immigrant visa or the location where you applied for an adjustment of status. To understand what are these two locations, you need to determine where you filed a request for your first green card.
Adjustment of Status
You may have applied for a green card when you were already located in the United States. In this case, you filed the Form I-485 application to acquire the adjustment of status. Therefore, you need to write the city and state of the USCIS office into the respective field (item 1, Part 3 on Form I-90).
You may have applied for an immigrant visa in your country. Therefore, you obtained your green card through consular processing. Fill out the city and country of the respective U.S. Embassy or U.S. Consulate where you applied for an immigrant visa.
Note that USCIS wants you to specify two locations in Form I-90. One location is where you applied for the visa or adjustment of status (item 1, Part 3, Form I-90), and another location is where you were granted the visa or adjustment of status (item 2, Part 3, Form I-90). To know more about the latter, follow to this article.