We often speak of a particular style of architecture. For instance, we say a certain house is an example of colonial architecture.
That means it is the kind of house that Americans built during the time, two hundred years or so ago, when the states were British colonies and not yet the independent United States. Or we speak of "Roman architecture." That means the kind of buildings that were built when the Roman Empire was the most powerful nation on earth, about two thousand years ago. Styles in architecture have changed much in the course of history. First, men have learned to do things better. There was a time when the best way to make a building strong was to use heavy blocks of hard stone.
There were no steel girders in those days. So architects of long ago designed their best buildings in marble or other hard stone, and architects today design their best buildings around steel. The outward appearance of the building changes because different materials are used. Before glass was invented, buildings looked different because they had no windows. Today, because glass is being made better and stronger every year, new buildings are likely to look almost as though they were solid walls of glass. Another reason that styles change is that men's ideas of beauty change.
Houses that were built seventy-five or a hundred years ago are called "Victorian" houses because that was the time when Queen Victoria was reigning in England. Victorian houses were quite fancy. They were considered very beautiful at the time, but people today consider them ugly because today people like their houses to be plain, and not to be decorated with all sorts of fancy curlicues and ornaments.
The cost of building has a lot to do with styles in architecture. Thousands of years ago, no one but kings and powerful noblemen could afford fine houses and buildings. There was little thought of the rights of human beings in those days. A powerful man would make slaves of men who were weaker, and of enemies he had conquered in warfare. The great structures of the past, such as the pyramids in Egypt and the great marble temples of Greece, could be built becausc thousands of slaves worked for many years, moving great blocks of stone, without being paid.
In a modern democracy like the United States, that would be impossible. But science has progressed so much that even stronger buildings are made in a few months, with far fewer men, all of whom are well paid for their work; and poor men as well as rich men can have strong, warm, comfortable houses to live in and office buildings and factories to work in.