Use reasoning to lead to the answer of the following question:
What could a massive building be if it is not constructed well?\nOptions:\n- insubstantial\n- massless\n- dwarf\n- inconsequential\n- good

insubstantial
Insubstantial means something not soild or strong in worth.

Even if the building is massive, if it is not well constructed, no one would go there making it useless and insusbstantial.

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Final answer: insubstantial