What an interesting concept, and very unlike the Romans, to me, from what I had been taught and learned about them regarding war, power, macho and idealized image… to share power!

 

Tetrarchy

One system of government of the ancient Roman Empire where power was split among 4 Co-emperors, 1 senior and junior each on the each and west sides of the vast empire

 

Co-emperor

One of several emperors sharing power in the Tetrarchy

 

Augustus (title)

A senior co-emperor in the Tetrarchy

 

Caesar (title)

A junior co-emperor in the Tetrarchy

 

Spandrel

The almost triangular space between one side of the outer curve of an arch, and the corner that fills out the side and top to make the arch rectangular in overall shape