This critical edition presents an unpublished album containing drawings of ancient architecture and architectural details, as well as imagined ancient buildings and sculptures by Francesco di Giorgio Martini, the Sienese architect, painter, sculptor and engineer, much admired by Leonardo da Vinci. The folios are tracings and constitute the largest known contiguous set of architectural drawings in the 15th century. They make intelligible the interrelation between the autograph sketches drawn on site and the illustrations in Francesco’s treatises. Throughout the 16th century, Francesco di Giorgio's studies of antiquity are a benchmark for everyone from Raphael to Palladio and Montano to Borromini. His drawings demonstrate the parallel practise of stereometric and perspective representations in the 15th century.