Apparently an unnamed cleaner, from the firm Chiarissima, thought it was left over garbage and tossed it. The works are estimated to be worth $15,000.
The city marketing commissioner told the BBC, "It's clear the cleaning person did not realize she had thrown away two works and their value. But this is all about the artists who have been able to better interpret the meaning of contemporary art, which is to interact with the environment. In any case, the insurance will cover the damages caused."
This isn't the first time that art has been confused with trash; back in 2001 an installation consisting of beer bottles, coffee cups, and overflowing ashtrays was thrown out by a cleaning crew.