Mayor Daley has said he wants the vandals to pay for the repair. He said he hopes the culprits are identified and forced to pay up. Security cameras near Michigan Avenue and Randolph Street may help with the investigation.
Park official Jill Hurwitz said the damage is minimal and the scratched names will be buffed out later this week. It is not clear how much it will cost.
The sculpture by artist Anish Kappor is officially called "Cloud Gate," but is commonly referred to as "The Bean" by Chicagoans. It is Kapoor's first public outdoor work installed in the U.S., according to the Millennium Park website, and one of the city's most popular tourist attractions.
The 110-ton elliptical sculpture is forged of a seamless series of highly polished stainless steel plates, which reflect the city's famous skyline and the clouds above, the site said.
A 12-foot-high arch provides a "gate" to the concave chamber beneath the sculpture, inviting visitors to touch its mirror-like surface and see their image reflected back from a variety of perspectives, according to the site.
A Look at 'The Bean':