[kalifese]

thank you, i understand now. that explains why every construction pic i see of high rise buildings being built in taiwan have no big deep hole with built structure in the ground.

but why is it in nyc/manhattan - which is a highly dense area of skyscrapers and highrises - they build bottom-up? i always see construction workers excavating a huge deep hole where they start the foundation and build the skeletal structure in and above it?