This paper proposes that the highly innovative panoramic cross-axial architectural compositions in Roman monumental and villa architecture come about very rapidly in stages from mid-3rd to late 1st centuries B.C. in a world in which a very mobile and cosmopolitan Roman senatorial elite and a Hellenisticroyal elite, with their professional staffs, formed a unitary, multi-polar international culture. The developmentof axial compositions, vs. mid-space compositional volumes of classical Greece, began in the 280s in Ptolemaic Egypt with Greek forms modified by influence of New Kingdom axial sanctuaries. From the mid-3rd to mid-2nd centuries enclosed agorai and sanctuaries develop cross-axial, often outward-facing panoramic designs (Lindos, Kos, Pergamon). From mid-2nd century, the innovative energy, the resources, and sometimes the architects, pass to the intensely competitive political environment of the Late Roman Republic (after the architects, pass to the intensely competitive political environment of the Late Roman Republic (after Pydna in 168 and the sieges of Corinth and Carthage in 146 B.C.). Axial, and soon cross-axial sanctuary and forum designs proliferate (Porticus Metelli, Gabii, Tivoli, Praenest, Forum of Caesar), usually in part inward facing,sometimes outward facing and panoramic (Praeneste, Tivoli). Such large compositions begin to affect large villa design by mid-1st century (Villa of the Papyri) and only after c. 50–30 B.C. panoramic outwardfacing colonnaded designs begin to be seen in architectural vignettes in wall painting (Villa San Marco, Stabiae), and actual villas (later additions to Oplontis, modifications and new villas at Stabiae, at the same time that there is an intense interest in elegiac landscape painting (Odyssey landscapes) and bucolic nature (Virgil,Georgics, c. 29 B.C.). The phenomenon seems to be a unified Mediterranean wide feature of elite culture since the same begins to be seen at Masada and Caesarea Maritima after Actium (31 B.C.).