More a figure of speech than a reality, but it is hard to find what you're looking for inside.

[He stops walking long enough to open the doors and let her enter first.]

The system of categorisation is one I don't recognise and books rarely are in the same place two days in a row, even though there's few enough people who frequent the building. There are ghosts that sometimes wander through, though. They're usually unobtrusive and pretty friendly, but they don't talk; they might mess up the organisation.

Also, surest way to the front if you can't remember is to follow one wall.