The Fall of the Roman Empire.

While such factors as corruption and political instability contributed to the fall of Rome, the primary reason for its demise was its size and inability to effectively managed that size. Though many things contributed to the empire's demise, those three things are the biggest factors. All of these 3 things together mixed with a lot of little things, caused the Roman Empire to fall. Corruption in Rome was widespread, both politically and socially. The rich ruled …

…the decline of the Roman state. Wealthy landowners avoided the heavy taxes by withdrawing from society altogether and making their own little communities. In the end, there was no money left to pay the army, build ships, or protect the borders. In the end, the fall of Rome was fundamentally due to over taxation, inflation, the sheer size of the empire, and it's own inability to regulate it's policies, and manage resources throughout its territories.