Maths Undergraduate Workroom, Warwick University
The UG workroom in the maths department is probably one of my favourite places on campus. It's a good place to work and the maths department itself is lovely. I figure leaving these here over the weekend might mean someone who has had to go in to work might pick one up and momentarily forget about their degree being hellish (trust me, it is). Moreover, the book itself is about a boy who loves maths and I doubt I'll be the only maths student who can relate to him. This is a stack of 5 books, so 5 different people can enjoy it. Here's another picture to show better roughly where I left this stack (although it's a bad picture because I felt self-conscious of there being other people around the room, sorry)
UPDATE: I returned here today (the day after) and noticed all of the books (plus the note) had gone. Yes!