Where any building, or wall, or anything affixed thereto, or any well, tank, reservoir, pool, depression, or excavation, or any bank or tree, is in the opinion of the Commissioner, in a ruinous state, for want of sufficient repairs, protection or enclosure, a nuisance or dangerous to persons passing by or dwelling or working in the neighbourhood, the Commissioner may by notice in writing require the owner or part-owner or person claiming to be the owner or part-owner thereof or failing any of them the occupier thereof to remove the same or may require him to repair, protect or enclose the same in such manner as he thinks necessary; and if the danger is, in the opinion of the Commissioner, imminent, he shall forthwith take such steps as he thinks necessary to avert the same.