Indeed, Mr. Eustis has added just three words to the text, which is otherwise reduced by about a quarter. The line “If Caesar had stabbed their mothers, they would have done no less” has been updated by the insertion of the words “on Fifth Avenue” before the comma. The audience roars.

The rest has been accomplished visually. David Rockwell’s set design combines timeless imperial imagery (giant gearlike constructions) with pointed American allusions. (A blowup of the preamble to the Constitution is prominently displayed.) Contemporary costuming by Paul Tazewell, including dark suits and trench coats, federal lapel pins, Anonymous masks and pussy hats, conjures today’s factional strife at a glance. Caesar’s wife, Calpurnia, wears a series of gorgeously cut outfits, appropriately in blush.

Neither as a citizen nor as a critic do I object to any of this. The first half of the play, culminating in that funeral scene, is great, nasty fun, even if, at the heart of Manhattan, it’s preaching to the choir. To the extent there is a problem with the Trumpification of “Julius Caesar,” both as politics and as dramaturgy, it arises in the second half, once Caesar, except for a brief recurrence as a ghost, disappears.

It is then that we are faced with the ways that Trump and Caesar never properly scanned, and an aftermath in which that confusion breeds more confusion. For one thing, Shakespeare’s Caesar is a war hero and, as smartly played by Gregg Henry, a deeply charismatic one. When offered the chance, three times, to become emperor, he chooses three times to remain a senator. This is more like George Washington than Mr. Trump.

So the assassination, though terrifically staged, is uncertainly motivated when a Trumpalike is its object. Whom are the conspirators really killing, and why? Brutus is the only one clearly thinking of his country first. By many accounts he is thus the play’s real protagonist, its tragic hero. Mr. Eustis’s production certainly endorses that reading.

But it is just as possible, and perhaps even more coherent, to see Caesar and his defenders, especially Marc Antony, as the heroes. Shakespeare, after all, was no anti-monarchist; that the Roman experiment in democracy ended with the elevation of Caesar’s great-nephew Octavius is not something he seems to weep over.