A monumental sculpture series by Chinese activist-artist Ai Weiwei was officially unveiled Tuesday outside of Toronto's City Hall.

Circle of Animals/Zodiac Heads will be displayed in the reflecting pool at Nathan Phillips Square in advance of the Art Gallery of Ontario's upcoming exhibit Ai Weiwei: According to What? — opening on Aug. 17.

Organized by the AGO and Tokyo's Mori Art Museum, the large-scale artwork is billed as the provocative artist's first major public sculpture. It offers a reinterpretation of the 12 animals that represent the traditional Chinese zodiac.

The zodiac's animals were most famously depicted in bronze as part of an elaborate fountain that Jesuit missionaries designed for the Summer Palace in Beijing. During the second Opium War of 1860, British and French troops set the palace ablaze and plundered its treasures, including the bronze heads.

"They are works that Ai Weiwei made in response to a series of works that were done in the late 1700s and taken away to Europe during the Opium Wars in the mid-19th century. He, in a sense, has repatriated them by remaking them and having us think about the relationship of contemporary China to Chinese history, and how it has been eroded by its relations with other countries," said AGO director Matthew Teitelbaum.

"They're powerful, they're very exciting to look at and they're outdoors in Nathan Phillips Square for over two months."

Ai, an outspoken critic of the Chinese government, remains unable to leave China ever since his 2011 detention, which came amid an overall crackdown against dissidents and activists.

The influential, internationally renowned artist — who creates sculpture, photography, installation, music, performance and other artistic works — currently has two major pieces on display in Italy, in conjunction with the Venice Biennale.

A play inspired by his 81-day incarceration also recently opened in London.

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The monumental sculpture Circle of Animals/Zodiac Heads by Chinese activist artist Ai Weiwei is being unveiled in Toronto in advance of the Art Gallery of Ontario's upcoming exhibit Ai Weiwei: According to What? (Andy Wong/Associated Press)