The rise of air-conditioning accelerated the construction of sealed boxes, where the building's only airflow is through the filtered ducts of the air-conditioning unit. It doesn't have to be this way. Look at any old building in a hot climate, whether it's in Sicily or Marrakesh or Tehran. Architects understood the importance of shade, airflow, light colors. They oriented buildings to capture cool breezes and block the worst heat of the afternoon. They built with thick walls and white roofs and transoms over doors to encourage airflow. Anyone who has ever spent a few minutes in a mudbrick house in Tucson, or walked on the narrow streets of old Seville, knows how well these construction methods work. But all this wisdom about how to deal with heat, accumulated over centuries of practical experience, is all too often ignored. In this sense, air-conditioning is not just a technology of personal comfort; it is also a technology of forgetting.