Every owner of real estate hereinafter maintaining any cellar,
vault, coal hole, or other excavation under the part of the street
or sidewalk which is adjacent to the part of his real estate, and
every person maintaining a post, pole, or other structure in a street
or sidewalk, or a wire, pipe, conduit, or other structure under a
street or sidewalk, shall do so on condition that such maintenance
shall be considered as an agreement on his part with the Town to keep
the same and the covers thereof in good repair and condition at all
times during his ownership and to indemnify and save harmless the
Town against any and all damages, costs, expenses, or compensation
which it may sustain or be required to pay, by reason of such excavation
or constructions being under or in the street or sidewalk, or being
out of repair during his ownership, or by reason of any cover of the
same being out or repair or unfastened during his ownership.