Caesar's Forum—inaugurated by C. Julius Caesar in 46 BC as dictator, and completed nearly 20 years later by his great nephew and adopted son and heir, Imperator Caesar Divi Filius in 29 BC—was the very first of the Imperial Fora of ancient Rome. It was largely excavated under Mussolini's reign in the 1930s and much of its extent is visible to visitors to Rome today. Yet it remains arguably the least studied and least understood of the great public spaces of the imperial capital. One of the most important reasons for this is that the main entrance or entrances into this forum remain unknown, and it is unclear how the open plaza and its associated buildings communicated with the other great public spaces all around it.

This paper examines the archaeological and literary evidence for the (eventual) monumental boundaries of Caesar's Forum; and it reviews the most important hypotheses that have been advanced about where the entrances to the forum may have been, and what connections the enclosed area may have had with the old Roman Forum and the Forum of Augustus. Finally we ask two questions. ‘What is at stake in attempting to decide between these conjectural proposals? And, ‘How do these different solutions—with regard to the permeability of the Forum's boundaries—affect the (perceived) symbolic character of the first Imperial Forum?'