After his consulship, Caesar spent 9 years in Gaul where he fought and defeated fierce Gallic and Germanic tribes, extending Rome's dominion into northern Europe and providing new sources of wealth for the Roman Empire.   While Caesar was in Gaul, Crassus was killed fighting the Parthians, and Pompey the Great began to turn against Caesar.  When Julia - wife of Pompey and daughter of Caesar - died in childbirth, relations between Pompey and Caesar worsened. Having conquered Gaul, Caesar intended to return to Rome. He knew that if he entered Italy unarmed, as Roman law required, he would be arrested.  Thus, in 49 BC, Caesar broke Roman law by leading his army across the Rubicon, the river that marked the northern boundary of Italy.  "Let the

dice fly high!" he is said to have shouted.  His action provoked a civil war with Pompey. Throughout the resulting turmoil, Caesar appealed to the Roman people for support - he had long been a popular figure.   As part of his popular appeal, he undertook numerous building projects in Rome - some to improve the city and others to inscribe a permanent memory of his rule. To rival the theater built by Pompey, his ally-turned-enemy, Caesar began to construct a theater near the Tiber River that would hold 15,000 spectators.  The theater wasn't finished when Caesar was killed in 44 BC and decades later his great-nephew and heir, Augustus, finished it and dedicated it to Marcellus, the son of Augustus's sister, Octavia.