2600 Citiplace Centre looks like it's located off of Corporate. If you're coming from College onto Corporate, Citiplace Centre should be the right, between Citiplace Dr. and Gates Circle. It looks like it's sharing a building with the Hancock Bank off of Corporate.
The phone number listed on the IRS website for this location is (225) 343-8625. The website also lists a 1-800 number that guarantees live assistance. That phone number is 1-800-829-1040.
Google maps often incorrectly shows the IRS office as being located on Balis Drive (near Perkins Road and College Drive) but this location is not correct.