Even though the island of Manhattan holds up tremendous millions of tons of steel, concrete, stone, and human bodies, it actually weighs less today than it did when only Indians and their teepees were on it! Amazing, but true!
The reason for that is because the weight of all the soil and rock dug out and dumped elsewhere to make way for subways, underground pipe lines, and building excavations weighed more than all the things added to the island.
