As the auction business comes roaring back to life on a wave of interest in historical art, impressionist and modern masterpieces have renewed their role as drivers of the market’s health. At the same time, a generation of auction house leaders is beginning to move on. Giovanna Bertazzoni started at Christie’s in 1997, when impressionist and modern art still dominated the scene and London played a central role in global art—positions to which they’re now returning, thanks in part to people like her. Recently, the 58-year-old Bertazzoni announced that she will be retiring this fall. I spoke to her about her career and plans for the future. As always, the following conversation has been edited for length and clarity.