This study focusses on the Roman Senate and its relation to the Emperors, taking a long-term perspective. The starting point is the observation, that the senators as a body held their sessions continuously from the 1st to the 6th century in the Curia Iulia/Diocletiana, a highly symbolic place in Roman mythical history. Visual, archaeological, epigraphic, numismatic and literary findings and records provide evidence of the complexity of role-playing and entangled interactions, which dictated the cooperation between SPQR and Caesares Augusti Imperatores throughout the centuries. By situational adaptions and accumulations of exempla of the past the two protagonists managed to maintain a precarious, varying, but perpetuated balance of powers. The Senate of Rome and the Roman Emperors were mutually dependent and intrinsically linked, forming a specific, bipolar authority structure, which was essential for the self-concept of the Roman State.