20. Peaceful progress not war
Often regarded as a miracle, the Pax Romana is certainly an extraordinary moment in history. This period of 200 years is known as long period of peace and stability for the Roman Empire. Prior the period of peace, the Romans were known for their focus on war. During the period of stability, the empire began to rebuild. Infrastructure like roads were built, a postal system was created and many beautiful pieces of cultural artwork emerged. Some hypothesize that without this time of Roman peace, the world we know may be very different.