You can go to your local health department for information on routine STI / STD testing
You can talk to your primary care doctor about routine STI / STD testing
Centers for Disease Control & Prevention Search Directory if you are located in the United States of America or a U.S.A. Territory — Learn More Here
European Centre for Disease Prevention & Control Search Directory if you are located in Europe United (EU) — Learn More Here
The STD Project: Resource to some  STI / STD testing/information organizations — Learn More Here