Section 755 ILCS 5/5-1 - Place of probate of will or of administration of estateWhen the will of a testator is probated or when the estate of a decedent or missing person is administered in this State, the probate or the administration shall be in the court of the county determined as follows:
(a) In the county where he has a known place of residence;(b) If he has no known place of residence in this State, in the county in which the greater part of his real estate is located at the time of his death; or(c) If he has no known place of residence and no real estate in this State, in the county where the greater part of his personal estate is located at the time of his death.