§ 103. Acquisition of lands. Whenever any real estate or interest therein shall be required for any municipal purpose, except as otherwise provided by law, the commissioner of public works may acquire for the city the necessary land and real estate by gift or by purchase, at a price approved by the board of estimate and apportionment, or by the proceedings specified in the eminent domain procedure law, or in the case of property required for street purposes, by the proceedings provided by law for acquiring and ascertaining damages for property taken for purposes of street openings.