Some particular books I found useful for A Game of Thrones and its sequels deserve mention... Life in a Medieval Castle and Life in a Medieval City, both by Joseph and Frances Gies. --George R.R. Martin, author of the series A Song of Ice and Fire
Medieval history comes alive in Joseph and Frances Gies's Life in a Medieval Castle, used as a research resource by George R. R. Martin in creating the world of Game of Thrones.
Newly reissued for the first time in decades, Life in a Medieval Castle is the bestselling classic that has introduced countless readers to the wonders of the Middle Ages. Focusing on a castle called Chepstow on the border between England and Wales, acclaimed Medievalists Joseph and Frances Gies offer an exquisite portrait of what day-to-day life was actually like during the era, and of the key role the castle played. The Gieses write eloquently about the many people whose lives revolved around the castle, from the lord and lady to the commoners of the surrounding village. We discover what lords and serfs alike would have worn, eaten, and done for leisure; the songs sung; and the codes of sexual conduct that maintained order. We learn of the essential role of honor in medieval culture, the initiation process undertaken by knights, and how castles attempted to keep the constant threats of outside violence at bay.
Exhaustively researched and as engaging as any novel, Life in a Medieval Castle is the definitive text for anyone wishing to learn more about this fascinating era.