How the Colosseum was built and why it was an architectural marvel
People keep saying the word &quot;concrete&quot;. I&#x27;m going to embarrass myself by asking what concrete is, and what it isn&#x27;t. I&#x27;ve looked it up and it seems to be a paste which can be made into any shape, and which then sets into stone. So its main properties are that it can be set into any shape, and when it hardens, it hardens into something strong and reliable.<p>Further questions:<p>-  Is there a difference between cement and concrete? What&#x27;s their relationship? Cement is also a paste which hardens into rock.<p>-  Is there a difference between mortar and concrete? What&#x27;s their relationship? Mortar is also a paste which hardens into rock.<p>-  What is the difference between concrete and stone? I guess the closest thing to &quot;setting&quot; stone is chiselling it, and that clearly takes longer than pouring and setting concrete.<p>So the main feature is that you can shape it without chiselling it.