The two most important new technologies that enabled the development of the skyscraper were

These two technologies were the development of a safe elevator and the method of building using a grid of steel beams. 

The elevator and mass-producing steel.

Explanation:

The fact that steel mass-production was developed was one of the most significant things that caused the advancement of skycrapers since steel made it much easier to design fortified solid structures than any another innovation in building sector. The many kinds of lifts also happened to make easier moving structure materials up and down, guaranteeing the wellbeing of laborers as well.

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