LOL, it is not an office, it's the border crossing between the USA and Canada. You can land there if you're returning from the USA.
http://en.wikipedia.org/wiki/Sault_Ste._Marie_International_Bridge
If you aren't able to enter the USA, I'm not sure whether or not you can "flag-pole" at SSM.
Here's the CBSA info for SSM (remember, tho, CBSA and CIC are different agencies).
http://www.cbsa-asfc.gc.ca/do-rb/offices-bureaux/261-eng.html