For what purpose?
The IRS does not publish an actual street address and often not even a PO Box anymore.
Most IRS mail is sent to:
City, State, Zip+4
The city, state and zip+4 varies depending on what you're sending them, whether it includes a payment or not and what state you live in.
The instructions for whatever form you're filling out will have the list of appropriate addresses.
Local Walk-in office
2525 Capitol St.
Fresno, CA 93721
5045 E Butler Ave
Fresno, CA 93888
For filing? Department of the Treasury, Internal Revenue Service,
Fresno, CA 93888-0002 if not enclosing a payment;
Internal Revenue Service,P.O. Box 7704, San Francisco, CA 94120-7704 if you are enclosing payment.
Fresno, Calif 93888
Have you tried to obtain this information from your local phone book or at the IRS website? Your answer may very well be there. Otherwise, trying calling them at 1-800-829-1040 and asking the person who answers the phone at this number.