70 ILCS 1560/1
The Commissioners of any park district located in whole or in part in any city having a population of 500,000 or more are hereby authorized and empowered to lease to a Metropolitan Pier and Exposition Authority, for a term not exceeding 40 years, any parcel or parcels of land, not exceeding 25% of the total park area of the park district, to be maintained and operated by the Metropolitan Pier and Exposition Authority for its lawful corporate purposes, including the construction, operation and maintenance of auditoriums or exposition buildings. The park district shall not thereby divest itself of ownership of the land demised or of its power to regulate the land. The Commissioners of the Chicago Park District shall not lease any park property under the provisions of this Act except property located in Burnham Park and shall not so lease more than 180 acres. The lease shall set out the terms and conditions, consistent with the statutory powers and duties of the lessor and lessee, upon which the land so demised may be used by the Authority, and may provide for its renegotiation and renewal for terms not to exceed 40 years. Neither the lease nor any renewal thereof shall be finally terminated while there is outstanding against the Authority any unfunded bonded debt.
70 ILCS 1560/1