Krzysztof Zygmunt Pac was an educated and intellectual man. He studied in Kraków, Liège, and for eight years at the University of Perugia in Florence, Italy. When he returned to the Commonwealth he obtained permission from Rome to establish a monastery for the Order of Camaldolese. The construction started in 1664 and eventually the completed monastery, now known as the Pažaislis monastery, is considered to be one of the best examples of baroque architecture in the lands of present-day Lithuania.
In 1673 Krzysztof Pac succeeded in passing a law stating that the convention of every third Sejm of the Polish–Lithuanian Commonwealth should take place in Grodno, a city in the Grand Duchy of Lithuania. He was also appointed Vilkaviškiselder.
He was married to Klara Isabelle de Mailly (~1631/35-1685), an authoritative woman. Their first-born son died at the age of eight days and they had no other children. Instead, Krzysztof Pac helped to launch his nephew's political career; he later continued to sponsor the expansion of the Pažaislis monastery.
Pac, his wife and their son, were all buried in the cemetery of the Pažaislis monastery. Their graves were robbed and vandalized several times during the monastery's eventful and long history. In 2003 they were properly reburied in a ceremony led by the archbishop of KaunasSigitas Tamkevičius.
