A most unusual thing happened in 1835. James Smithson, a little-known British scientist who had never visited the United States, left a fortune to the country whose democracy he so admired. The bequest eventually gave rise not only to the Smithsonian Institution Building—better known as the Smithsonian Castle—but also to more than twenty museums in the Smithsonian system. Today the red sandstone of the Castle’s Romanesque façade glows warmly against the cool marble of the other buildings on the National Mall. Yet the story of the stones is just as strange as that of the institution that they grace. The Seneca Quarry—the source of the red sandstone—lies hidden in the woods twenty-three miles up the Potomac River from Washington, D.C. It was a boom–bust ride for the quarry, which opened and closed, saw its first developer John P.C. Peter die, filed for bankruptcy twice, suffered through floods, and contributed to a national scandal that embarrassed the Grant presidency and helped bring down the Freedman’s Bank. Author Garrett Peck unearths a history never before told of the quarry owners and emancipated slaves who toiled there, and the many people who work to this day to save Seneca. Join Peck as he traces the unlikely story of the Smithsonian Castle and the Seneca Quarry.