I am trying to figure out when my apartment complex built

Does apartment complex have a web site ? Have you went, most likely in person, to the zoning or code office and looked up plans for the construction with dates ?

What makes you think there is a website that would tell you? Not all info is on the web.

You can try the county recorder of deeds to see if there is a web site with county records.

The historic society may be able to help as well if the building is older. You could also read up on your community history. You'd be surprised what you can find when you get creative in searching