To help preserve pre-Revolutionary history of American food and drink, Mars, Inc. announced that its American Heritage line of chocolate, coffee & tea is available in the only 18th century coffeehouse in the United States, appropriately located in Colonial Williamsburg, Va. R. Charlton’s Coffeehouse, which was just recently reconstructed as the newest exhibition at the historic site, provides guests with the opportunity to enjoy a sampling of coffee, tea  a la 18th century style.