Mayor de Blasio’s “Advisory Commission on City Art, Monuments and Markers” is the most terrifying news out of City Hall since the cornerstone was laid in 1803.

Goodbye, hundreds of years of history, tradition and respect for our shared past. Hello, a Communist/Fascist-style imposition of cultural martial law. Good luck, Chris Columbus!

Who’s on the panel almost doesn’t matter. Merely setting up such a body shows depraved indifference to the rights and views of 8.4 million New Yorkers. It’s an obscene embrace of identity politics at the expense of pluralism, the room-for-everyone ideal that’s historically our great city’s strength.

Be no less frightened that the announcement’s language is so vague, it could be interpreted in a million ways.

De Blasio’s “experts” will come up with “guidelines” to acknowledge “values that matter to us as New Yorkers.” Which New Yorkers does de Blasio mean? The “whopping” 17 percent of 4.3 million registered voters who pulled the lever for him in the record-low voter-participation year 2013?

His “experts” will look at monuments “seen as oppressive and inconsistent with the values of New York City.” But which New York City, where 36 percent of the population is foreign-born and an estimated 800 languages are spoken?

Exactly what are New York City “values?” Are they the same ones that Texas Sen. Ted Cruz attacked Donald Trump, of all people, for supposedly upholding during last year’s presidential race?

Since the mayor will have the final say, it’s clear he means his own values. He made no secret what they are in this week’s New York Magazine: a detestation of private-property rights and no little sympathy for a “socialistic” system that would let City Hall make every decision about everything, no objections please.

New Yorkers must call on the commissioners to do the right thing: quit before they start and let de Blasio bring shame to the city all by himself.