735 ILCS 5/3-104
Jurisdiction to review final administrative decisions is vested in the Circuit Courts, except as to a final order of the Illinois Educational Labor Relations Board in which case jurisdiction to review a final order is vested in the Appellate Court of a judicial district in which the Board maintains an office. If the venue of the action to review a final administrative decision is expressly prescribed in the particular statute under authority of which the decision was made, such venue shall control, but if the venue is not so prescribed, an action to review a final administrative decision may be commenced in the Circuit Court of any county in which (1) any part of the hearing or proceeding culminating in the decision of the administrative agency was held, or (2) any part of the subject matter involved is situated, or (3) any part of the transaction which gave rise to the proceedings before the agency occurred. The court first acquiring jurisdiction of any action to review a final administrative decision shall have and retain jurisdiction of the action until final disposition of the action.
735 ILCS 5/3-104