In the Italian Renaissance, architects turned to antique sources such as Pliny and Vitruvius as they began to open up domestic space to light, air and landscape. Instead of relying on the thermal inertia of the thick-walled mediaeval castle, they enlarged windows and added loggias to both villas and palaces. Inspired by the ancients, they incorporated seasonal flexibility into their designs, allowing vertical or horizontal shifts from one apartment to another according to the time of year.