Romans had several beliefs of how their city was founded.
One was that a defeated Trojan escaped from war to Latium and married a princess and their children founded Rome.
Another belief was that two half-blood twins,Romulus and Remus, one human parent the other a god, were thrown into a river by a jealous uncle and saved by a she wolf. These twins had a dispute over where the best place to start a city was and Romulus killed Remus and founded Rome on Palatine Hill.
I think that Roman Emperors was the the most important idea we learned about ancient Rome. This idea was important because Roman Emperors could affect the entire roman race. They could change laws, declare war, and they could use government money for outrageous purposes. Obviously, learning about Roman Emperors was very important.