I have always been amazed at the architecture of old, and the Colosseum is no exception. Built at the height of the Roman empire, what surprises me was her ability to withstand the tides of time, and still remain strong as ever, although a 'little chipped' I must say. The details of her inner workings are indeed amazing, and it goes to show the kind of details and effort that the builders must have put into in order to ensure that this was indeed the epitome of what a place of entertainment should be during her heydays, non-withstanding the sometimes sordid and gruesome intent of some of the activities that happens there, by modern-day standards.
And what was truly enlightening were the key concepts derived from such an amazing feat of architecture, that are still currently used today in modern-day stadiums and the likes. Indeed the physical architecture might have changed with better engineering and machinery, but the concepts upon which the Colosseum was built, are still just as relevant today, as they were thousands of years ago!