Why was steel a more effective building material than iron in the late 1800s?

Before the 1800s, builders used cast iron. But they found that structural steel beams set in concrete allowed them to frame tall buildings that were more fire resistant and more structurally sound than cast iron. Since that time, steel has not only become the best building material for commercial construction but closely tied to economic health.

In the late fifteenth century, a major world power that established colonies in the era of old imperialism was france or germany or spain. their colonial activity was mainly limited to america or africa or asia.

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