Nicole le Douarin has shown a long lasting interest for developmental hematopoiesis. Starting from her early research experience, we travel along the main discoveries and concepts that have shaped the modern view of developmental hematopoiesis. All through, we survey the seminal contribution of the "Ecole de Nogent" about lymphocyte homing and the discovery of endothelial-specific tyrosine kinases. This interview is a promenade through the past and present of developmental hematopoiesis narrated by an exceptional personality and an outstanding scientist.