Steel is a dense material that can be stretched and squeezed to great extremes without breaking or snapping. In this regard, it's a good choice for a very tall building in a gusty city. In fact, the tallest building in the United States, the Sears Tower in Chicago, is made entirely of steel.
But while steel is very strong at normal temperatures, it loses its strength and melts when the temperature rises above 700 degrees Fahrenheit. For this reason, all steel buildings must be fireproofed to slow the heating of its columns and beams in a fire.
There are many ways to fireproof a steel building. Hint: one way to make a steel building more fire-resistant is to insulate the steel with a fireproof material ... like concrete!