CNN Travel – Rome might not have built ancient history’s biggest empire – a shout out to Genghis for that one – but it was undoubtedly the most enduring and influential. That’s because Roman passions for outrageous, oversized architecture went hand in hand with detailed record-keeping and relentless imperial PR. As a result not only have a huge number of landmark sites survived to this day, but we also know a lot about them.

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