BMD : Intro : Page 2
Unfortuantely, with the demise of the Roman Empire around AD 600, much of their engineering prowess vanished, not to be reborn for hundreds of years. Castle and city construction during the Middles Ages was much more along the lines of the Egyptians, piling lots of large, shaped stones one atop another to create those structures.
While this engineering philosophy works quite well, it is not time or material efficient. Castles and cathedrals often took decades - or even centuries - to complete. Building techniques for smaller structures, like houses, also stayed relatively unchanged from the Middle Ages to the early 1900's. For even simpler buildings, like sheds and dog houses, we still use simple construction techniques, like houses and other small buildings did 100 years ago.
Fortunately for us, the late 1800's and early 1900's saw several engineers around the world thinking about how to improve upon previous technology or to replace it with new methodologies. The widespread availability of steel, which is much stronger than its constituent parts (iron, carbon, and some other elements), the ability to shape the steel using big machines and extruding dies, and the new ability to transport the shaped building materials via rail and large ships made new thinking possible.