My recent visit to Madrid revealed only a few townhouse neighborhoods, but the day before I flew home, the folks at Estudio Entresitio graciously made some time for me to discuss their projects and design philosophy: applying simple geometric rules to create spaces that assemble into a unified design. They have designed a pair of townhouses in Madrid, but more interesting is their 43 Viviendas project in Almuradiel, Ciudad Real, which was designed by applying geometric rules to break a large site into 43 townhouses, and each townhouse into spaces and voids. But they also applied a human touch, differentiating north- and south-facing units to maximize daylight.