Hospital of Santa Maria Nuova
The Hospital of Santa Maria Nuova was founded in 1288 by Folco Portinari, following the urging of his family matriarch. Over the centuries, the institution would become increasingly rich and powerful due to donations of both money and artwork, receiving even a visit from Pope Martin V in 1419.
This hospital would, around 1507, provide the location and resources needed for da Vinci to perform his careful and thorough dissections of human cadavers, including an elderly gentleman whose death he personally witnessed. In the time he worked at this institution, Leonardo would dissect upwards of 30 corpses, using techniques such as wax modeling to observe the anatomy of the cranial cavities, and creating glass replicas of the aorta to study fluid flow.
Sources:
"Hospital of Santa Maria Nuova." https://en.wikipedia.org/wiki/Hospital_of_Santa_Maria_Nuova. Accessed 8 Mar. 2018.
"Leonardo da Vinci: Anatomist."