Cornelis de Graeff was also the founder of a regent dynasty that retained power and influence for centuries and produced a number of ministers. He was Lord of the semisouverain Fief ("allodiale hoge heerlijkheid") Zuidpolsbroek and an Ambachtsheer ("Lord of the Manor") of Sloten, Sloterdijk, Nieuwer-Amstel, Osdorp and Amstelveen, near Amsterdam, and castlelord of Ilpenstein. De Graeff was also President of the Dutch East Indies Company, and a chiefcouncillor of the Admiralty of Amsterdam. Like his brother, Andries De Graeff, he was an art collector and patron of the arts.