I work at a hospital and bikes are not allowed to be brought inside. There is a locked, fenced-in compound where I park my bike. I still, however, lock it to the rack inside the compound with a heavy-duty u-lock and square-link chain (with its own mini u-lock). You never know if another cyclist will forget to lock up the compound on the way out or, God forbid, make off with your bike. The compound is also under video surveillance which offers some added security.