Last week, Mayor Bloomberg and a cadre of arts enthusiasts from the Public Art Fund gathered at City Hall Park to officially open a retrospective on conceptual artist Sol LeWitt titled Structures, 1965-2006. Comprised primarily of sleek white cubes and forms and one colorful Splotch, the installation of 27 sculptures represents the first outdoor retrospective of LeWitt’s work as well as the largest public art display at City Hall Park, billed by Nicholas Baume, chief curator for the Public Art Fund, as New York’s “museum without walls.”

Joined by Baume and LeWitt’s wife and daughters, Bloomberg strolled through the park grounds to take in the striking white works of art, many of which have never been publicly displayed in the United Stated before. LeWitt’s Structures, with their ruggedly geometric forms, seem at once a seamless part of the surrounding urban and natural landscapes.

“City Hall Park and its environs in Lower Manhattan offer a perfect location to reconsider LeWitt’s structures,” said Baume in a statement. “His geometric, white forms contrast with the organic, picturesque park setting, while they also resonate strongly with the surrounding Manhattan grid and the stepped profiles of its signature skyscrapers. The later work, with its complex and irregular forms, anticipates the vocabulary of more recent architecture, including Frank Gehry’s undulating new tower at 8 Spruce Street.”

A variety of modular and open cubes, the breakthrough pieces for the artist in the 1960s and 1970s, are scattered about the park, their scale defying the outward simplicity of their form. Complex Forms, with sharp angular edges recall many recent Manhattan skyscrapers such as the Bank of America Tower, and LeWitt’s late, colorful work–Splotch 15–defies categorization. Take a look at many of the sculptures in the gallery below.

The exhibition is ongoing through December 2, 2011.