It was a curious spectacle on Wednesday as an unexplained art project took shape on the side of the former Hancock Tower (its owners insist we call it 200 Clarendon now).

Then on Thursday, after much speculation, came the big reveal.

The work, a four-story fuzzy black-and-white image of a man, is a piece by the French artist known as JR. It's the artist's New England debut, according to a release Thursday morning from Boston Properties, which owns the iconic Boston building. 

The image is based on a picture JR took and is "meant to be anonymous and mysterious, devoid of any landmarks that might give away its location," the release said.

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The roll-out of the piece, shrouded in mystery, was no mistake, the real estate investment trust said.

"JR prefers for the artwork to emerge quietly, for the city to respond to the imagery. Creating a sense of surprise and tension as the image slowly materializes 500 feet in the air. What will it be? Why is it there? What does it mean?" 

Plenty took to Twitter Wednesday to do just that, speculating that it might be an ode to Yogi Bera, or maybe something from Banksy, the street artist and pop culture icon similarly inspired by anonymity. 

When it's done, the installation would be 150 feet wide by 86 feet tall, the release said, and would stay there through mid-November ("a glorious farewell to summer," Boston Properties proclaimed).

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Boston art maven Pedro Alonzo curated the piece, the final in a series of temporary public art installations at the building. The tower has been on an artistic streak lately. Earlier this year it was host to a colorful, block-long installation by the artist MOMO in the building’s bottom floor.

"200 Clarendon Street has long been an iconic structure on Boston's skyline," said Bryan Koop, the company's senior vice president, in a statement. "We are thrilled to have JR use the building as a canvas for his iconic work."

JR (his real identity is kept secret) won the TED prize in 2011. In a speech, he pledged to "use art to turn the world inside out."