In 1968, Nugent, Vollman, and Ruml posed a set of quadratic assignment problem instances of sizes 5, 6, 7, 8, 12, 15, 20, and 30. The instances were posed in the paper, "An experimental comparison of techniques for the assignment of facilities to locations" appearing in the journal "Operations Research".

Peter Hahn has written an excellent article on progress in solving the Nugent QAP instances. With his permission, the paper is available here in PDF and Postscript formats.