Room 556 is on Level 5, Sharp Centre for Design, 100 McCaul Street. To get to Level 5, the easiest way is to take the Express Elevators in the main elevator lobby.
Once on Level 5, turn right and walk straight through the corridor. At the end of the corridor you will reach a large open space (known in the floor plans as the Open Studio). Walk straight ahead (about 20 steps) and you will reach several tables with two printers and several computers. Turn left and walk straight ahead through a short corridor into the Teknion Environmental Design Centre.
Turn right at the corner and continue walking straight ahead. Ignore the fact that the first room you see on your left is numbered 558. The second room on your left is Room 556.