FlorenceĀ Sloane began her extensive millstone collection in 1931. Now considered works of art, these centuriesā€™ old pieces of stone once served as tools to grind wheat into flour. The grinding abilities of millstones were also employed in cork mills, dye mills, flint grinding mills, hemp mills, paint and color mills, and the chocolate industry.

The first 29 millstones collected reside in the southeast end of the gardens. Another 47 millstones are arranged in a compass-like pattern at the west entrance of the Hermitage, fittingly named the Millstone Courtyard. Florence Sloane collected these millstones from mills in Virginia, North Carolina, Pennsylvania, Maryland, and Georgia. In total, 105 millstones are scattered throughout the property.

Mrs. Sloanes ambitious endeavor to collect these industrial objects as things of beauty pays homage to the millstone makers: hardworking tradesmen turned accidental artists.