Wood-paneled libraries, sumptuously appointed interiors, mudrooms, paddocks, and stables are all signature elements of an equestrian-based style that is aspired to across the country, from Lexington, Kentucky, to Potomac, Maryland, and Greenwich, Connecticut. The beginnings and epitome of this style of interiors and architecture are to be found in Middleburg, Virginia, where for centuries a lifestyle and architecture have been honed to produce some...