jeffk said:
Secret doors in Evans and Cushing - check.
Front balcony and roof of Admin building - check.
Steam tunnels - sadly not checked.
At one time, they had a guard at each of the doors of Evans Library. Whenever you were leaving, they would check to see if any library books you might have had been checked out. To the best of my recollection, it was always fairly old men who checked your books at the doors.
Also, there was a computer center on the second floor of Cushing. They would routinely change the layout, but usually you would get to it through the stacks. For a while, there was a second door that you could go through to leave through Cushing instead, but I don't think that most people noticed that door.
So when they had both ways in and out of the computer center, you could exit the library through Cushing and avoid the old men at the main doors of Evans completely.
Later, when they opened the new entrance on the East side and closed the North and South entrances, they installed a system of little magnetized strips in the books. When you would check out the book, they would run it over the scanner so it wouldn't set off the alarms.
Once while I was a grad student, I had a fairly large book checked out and I could see the magnetized strip in it the binding. I reached in and pulled it out to look at it. When I checked the book in, the guy at the desk was puzzled that it didn't have a magnetized strip and so he set it aside to put a new strip in it.
A couple of weeks later, another grad student and I went to the library and found a large book where we could easily remove the magnetized strip. We then took that down to to the first floor and waited for someone to walk by with easy availability of planting the magnetic strip on them. After a couple of minutes, one girl walked by with a sweater with a hood on it (it was winter) and so we dropped the magnetic strip into her hood and then sat back to watch the fun.
Sure enough, when she walked through the detector, they started buzzing. They didn't have a guard at the time (sometimes they did and sometimes they didn't) and since she had a completely clean conscience, she never even thought that it might be her setting off the alarm and so she just calmly kept walking. That took all the fun out of it and so we never tried that again.