Section 556 - Disposition of property1. An agency may sell, lease for a term not exceeding ninety-nine years, or otherwise dispose of any real property and appurtenances thereto or any interest therein acquired by it pursuant to section five hundred fifty-five of this article, to any person, firm or corporation at the highest marketable price or rental at public auction or by sealed bids.2. Notwithstanding the provisions of subdivision one of this section, such real property and appurtenances thereto may be sold, leased for a term of not exceeding ninety-nine years or otherwise disposed of for the effectuation of any of the purposes of an urban renewal program in accordance with the urban renewal plan pursuant to the provisions of subdivision two of section five hundred seven of article fifteen of this chapter.3. Any deed, lease or instrument by which real property and appurtenances thereto, or air rights and concomitant easements or other rights of user necessary for the use and development of such air rights over streets, alleys, highways or other public rights of way, railway or subway tracks, bridge or tunnel approaches or entrances, or other similar facilities, or air rights sites and necessary sitework, the foundations and platforms constructed or to be constructed in connection therewith, or any interest therein is conveyed or disposed of pursuant to this section shall contain provisions requiring the purchaser, lessee or grantee to replan, clear, rehabilitate, restore, renew, conserve, improve, reconstruct or redevelop such property in accordance with the urban renewal plan, as approved by the governing body, and within a definite and reasonable period of time, subject to the terms of the contract relating thereto between the agency and the sponsor and provisions insuring the use of such real property for purposes consistent with such urban renewal plan.4. Notwithstanding anything to the contrary in this article or article fifteen of this chapter and notwithstanding any provision of any general, special or local law, such real property and appurtenances thereto may be sold, leased for a term not exceeding ninety-nine years, exchanged with or otherwise disposed of, for the effectuation of any of the purposes of the urban renewal program in accordance with the urban renewal plan, to any municipal corporation, school district, fire district, housing authority, the state of New York, or the government of the United States and any agency or department thereof, for a valuable consideration and upon such terms and conditions as shall be approved by the governing body of the municipality, without public auction or sealed bids or public notice.