How do I find out when a Sears store was built?

I'm doing a bit of research in my free time, and I can't seem to find when my local Sears or the shopping center it is in was built. Does anyone know how I could find this information? It is the Sears in East Northport, NY in Huntington Square (formerly Huntington Square Mall). If anyone could help me find this out, that'd be greatly appreciated!