The Senate named Caesar dictator perpetuo ("dictator in perpetuity"). Roman mints produced a denarius coin with this title and his likeness on one side, and with an image of the goddess Ceres and Caesar's title of Augur Pontifex Maximus on the reverse. According to Cassius Dio, writing over 200 years later, a senatorial delegation went to inform Caesar of new honors they had bestowed upon him in 44 BC. Caesar received them while sitting in the Temple of Venus Genetrix, rather than rising to meet them.
Suetonius wrote (almost 150 years later) that Caesar failed to rise in the temple, either because he was restrained by Cornelius Balbus or that he balked at the suggestion he should rise. Suetonius also gave the account of a crowd assembled to greet Caesar upon his return to Rome. A member of the crowd placed a laurel wreath on the statue of Caesar on the Rostra. The tribunesGaius Epidius Marullus and Lucius Caesetius Flavus ordered that the wreath be removed as it was a symbol of Jupiter and royalty. Caesar had the tribunes removed from office through his official powers. According to Suetonius, Caesar was unable to dissociate himself from the royal title from this point forward. Suetonius also gives the story that a crowd shouted to him rex ("king"), to which Caesar replied, "I am Caesar, not Rex" ("Ego caesar, non rex."). Also, at the festival of the Lupercalia, while he gave a speech from the Rostra, Mark Antony, who had been elected co-consul with Caesar, attempted to place a crown on his head several times. Caesar put it aside to use as a sacrifice to Jupiter Optimus Maximus.
Plutarch and Suetonius are similar in their depiction of these events, but Dio combines the stories, writing that the tribunes arrested the citizens who placed diadems or wreaths on statues of Caesar. He then places the crowd shouting "rex" on the Alban Hill with the tribunes arresting a member of this crowd as well. The plebeian protested that he was unable to speak his mind freely. Caesar then brought the tribunes before the senate and put the matter to a vote, thereafter removing them from office and erasing their names from the records.
Suetonius adds that Lucius Cotta proposed to the Senate that Caesar should be granted the title of "king", for it was prophesied that only a king would conquer Parthia. Caesar intended to invade Parthia, a task that later gave considerable trouble to Mark Antony during the second triumvirate.
His many titles and honors from the Senate were ultimately merely that: honorary. Caesar continually strove for more power to govern, with as little dependence as possible on honorary titles or the Senate. The placating and ennobling of Caesar did not allay ultimate confrontation, as the Senate was still the authority granting Caesar his titles. Formal power resided in them, resulting in tension with Caesar.
Brutus began to conspire against Caesar with his friend and brother-in-law Gaius Cassius Longinus and other men, calling themselves the Liberatores ("Liberators"). Many plans were discussed by the group, as documented by Nicolaus of Damascus:
The conspirators never met exactly openly, but they assembled a few at a time in each other's homes. There were many discussions and proposals, as might be expected, while they investigated how and where to execute their design. Some suggested that they should make the attempt along the Sacred Way, which was one of his favorite walks. Another idea was to do it at the elections, during which he had to cross a bridge to appoint the magistrates in the Campus Martius. Someone proposed that they draw lots for some to push him from the bridge and others to run up and kill him. A third plan was to wait for a coming gladiatorial show. The advantage of that was, because of the show, no suspicion would be aroused if arms were seen. The majority opinion, however, favored killing him while he sat in the Senate. He would be there by himself, since only Senators were admitted, and the conspirators could hide their daggers beneath their togas. This plan won the day.
Nicolaus writes that in the days leading up to the assassination, Caesar was told by doctors, friends, and even his wife, Calpurnia, not to attend the Senate on the Ides for various reasons, including medical concerns and troubling dreams Calpurnia had:
...his friends were alarmed at certain rumors and tried to stop him going to the senate-house, as did his doctors, for he was suffering from one of his occasional dizzy spells. His wife, Calpurnia, especially, who was frightened by some visions in her dreams, clung to him and said that she would not let him go out that day. But [Decimus] Brutus, one of the conspirators who was then thought of as a firm friend, came up and said, 'What is this, Caesar? Are you a man to pay attention to a woman's dreams and the idle gossip of stupid men, and to insult the Senate by not going out, although it has honored you and has been specially summoned by you? But listen to me, cast aside the forebodings of all these people, and come. The Senate has been in session waiting for you since early this morning.' This swayed Caesar and he left.
Caesar had been preparing to invade the Parthian Empire (a campaign later taken up by his successor, Mark Antony) and planned to leave for the East in the latter half of March. This forced a timetable onto the conspirators. Two days before the actual assassination, Cassius met with the conspirators and told them that, should anyone discover the plan, they were to turn their knives on themselves. His successors did attempt the conquests of Parthia and Germania, but without lasting results.