Book excerpt: Robert de Gast, author of the popular The Doors of San Miguel de Allende crosses the thresholds of homes in this historic Mexican town to discover their remarkable outdoor paradises--sunstruck, lushly colored courtyards, patios, and breezeways--that lay beyond them. Come with de Gast as he guides viewers to parts of San Miguel visitors seldom see and offers glimpses into the daily lives and traditions of those who live in this unique place. Established in the sixteenth century as a Franciscan mission, the lovely town of San Miguel de Allende has been an art and artisanal center for nearly two centuries. Its cool summers and mild winters have more recently made it a popular destination for vacationers from North America and Europe. A part-time resident of San Miguel since 1991, Robert de Gast is an award-winning photographer and a widely published writer. His avocations include hot-air ballooning, which he pursues in Mexico, and sailing, which he does for part of the year on the East Coast of the United States.