Toward the middle of the eighteenth century, the monumentality of Baroque architecture gave way to Rococo, which emphasized delicacy, playfulness, and refined ornamentation. Frederick II’s Sanssouci Palace in Potsdam near Berlin is one of the most celebrated examples of the Rococo style. Intended as a sanctuary and summer retreat, Sanssouci was reserved for the monarch’s private pursuits. It was there that he hosted privileged guests, such as the French philosophe Voltaire (1694-1778), who stayed at Sanssouci from 1749-53. The image below is from a boite d’optique (peep box), an early stereoscopic device popular in the seventeenth and eighteenth centuries.