Where did it happen? APS is identifying historic physics sites in the United States. Once a site is recognized for historic importance, a brass commemorative plaque is presented in an installation ceremony. You can see the sites and submit nominations online.
Historic Sites Initiative
When did it happen? Since 2000, APS News has featured, "This Month in Physics History" in every issue. Skim the headlines. Maybe you'll find a significant discovery occurred on your birthday.