(1) Where any building or any part thereof is within the regular line of a public street and in the opinion of the Commissioner it is necessary to set back the building or part thereof to the regular line of the street he may, by notice served on the owner in accordance with the provisions of this Act, require him to show cause within such period as may be specified in the notice as to why such building or part thereof which is within the regular line of the street should not be pulled down and the land within the regular line acquired by the Commissioner on behalf of ¹[²[the Corporation]].
     (2) If such owner fails to show cause as required by sub-section (1) the Commissioner may, with the approval of the Standing Committee, require the owner by another notice to be served on him in accordance with the provisions of this Act, to pull down the building or part thereof which is within the regular line of the street within such period as is specified in the notice.
     (3) If within such period the owner of the building fails to pull down the building or part thereof as required by the Commissioner, the Commissioner may pull down the same and all the expenses incurred in so doing shall be paid by the owner and recoverable from him as an arrear of tax under this Act.
     (4) The Commissioner shall at once take possession on behalf of ¹[²[the Corporation]] of the portion of the land within the regular line of the street occupied by the said building or part thereof and such land shall thereupon be deemed to be a part of the public street and shall vest in ¹[²[the Corporation]].