How could build a skyscraper?
Such a miracle as a skyscraper, would not have been possible without the invention of steel frame. Assembling the steel frame - the most dangerous and difficult part of construction. It is the quality and speed of assembly frame determines whether the project is implemented on time and within budget.
I recommend for viewing.

 Those architectures are beautiful, they looks strange but also are very creative and value. Barcelona looks beautiful with those. They are cool, amazing, weird, beautiful, you may call those as you want but you must agree that those buildings are genius and remarkable.