If a city of the first class has acquired title to land for public auditoriums or art museums, it may let it or any part thereof, together with the structures and improvements constructed or to be constructed thereon for such term as may be deemed proper and may raise the needed funds for financing the project, in whole or in part, by transferring or pledging the use and income thereof in such manner as the corporate authorities deem proper.

Any lessee under any such lease may mortgage the leasehold interest and may issue bonds to be secured by the mortgage and may pledge the rent and income of the property to accrue during the term of the lease or any part thereof for the due financing of the project: PROVIDED, That the corporate authorities may specify in any such lease such provisions and restrictions relating thereto as they shall deem proper.