65 ILCS 5/9-2-24
Every person who is named in the commissioners' report as an owner of property to be taken or damaged for the improvement, and every person who is therein named as an occupant of any parcel thereof, shall be made a party defendant in the proceeding. All other persons having or claiming interest in any of the premises shall be described and designated as "all whom it may concern," and by that description shall be made defendants. Upon the filing of the commissioners' report, a summons shall be issued and served upon the persons made party defendants, as in other civil actions, except that the summons shall require a defendant to appear within 15 days after service, exclusive of the day of service. As to such of the defendants as are shown by the affidavits to be non-residents of the State of Illinois, or whose residences are shown thereby to be unknown, and the defendants designated as "all whom it may concern," the clerk of the court shall publish in one or more newspapers published in the municipality, or, if no newspaper is published therein, then in one or more newspapers with a general circulation within the municipality, a notice of the pendency of the proceeding, the parties thereto, the title of the court, the time and place of the return of the summons in the case, the description of the property to be taken or damaged, the total cost of the improvement as shown by the estimate and report, and the nature of the proceeding. This notice shall further state that a special assessment has been made to raise the cost of the improvement, and the time and place of filing the report thereof. This notice shall be published at least once in each week for 3 weeks, the first notice to be published at least 30 days before the return day of the summons.
65 ILCS 5/9-2-24