65 ILCS 5/11-45-12
The commissioners shall determine when they will proceed with the purchase of a building or site, or with the erection of a band-shell or similar structure, or with the remodeling, repairing and equipment, or any other proceeding permitted hereunder. They may proceed at once or determine to wait and allow the fund to accumulate. If the commissioners determine to let the fund accumulate, they shall invest the money in interest paying securities such as are authorized by law for the investment of public funds, thereto remain until the same is needed for proceeding hereunder. The commissioners may contract for the expenditure of such funds for the purposes herein designated and may apply the proceeds of the tax and bonds issued hereunder, toward payment therefor.
65 ILCS 5/11-45-12