Copyright Christie's Images Limited 2010

Does the drawing at left look familiar? It should, if you were paying attention during that Renaissance and Baroque survey course. It’s one of Gian Lorenzo Bernini’s studies for the Louvre, drawn in this case by his right hand, Mattia de Rossi, in black chalk, pen and brown ink, and gray wash. Long overlooked in the family collection of the electors of Hanover, the 19½-inch-wide drawing went up for auction at Christie’s London on July 7. The estimate was a mere $30,000–$40,000—a steal for such a remarkable piece of architectural history.