"If you stretched out all of the shelves in all of Harvard's 73 libraries...(and if the data were made up)"

Length of shelf in miles:

For markers: Navigate to where you'd like to start plotting the cumulative miles Harvard's library 12 million holdings would occupy if arranged on a single shelf. Click on the book icon in the center of the map to create the circle, and then click anywhere on the edge of the circle to draw the shelf. Hover over the markers to see which subject they denote. Drag the book to where you want the center to be.

For circles: Click on the book icon. Or drag it to where you'd like the center of the circles to be.

[Note that I'm using the ten top-level Dewey categories, which the Harvard Libraries don't use. I looked up keywords in the subject fields, sometimes using Dewey subfields and sometimes just the top-level category, insuring inaccurate results. I also made up the total length of the shelves, assuming that the average width of each of Harvard Libraries' 12 million holdings is one inch. Version 0.01, January 19, 2011]