What is one way that city landscapes changed in the beginning of the twentieth century? The first skyscrapers were built.
The first tenement apartments were built.
The first structures using steel were built.
The first transportation systems were built.

C. The first structures using steel were built.

polisit can also mean a body of citizens. in modern historiography, polis is normally used to indicate the ancient greek city-states, like classical athens and its contemporaries, and thus is often translated as "city-state". the body of citizens came to be the most important meaning of the term polis in ancient greece.