A smattering of the world’s most iconic buildings — including the Empire State Building and the former Sears Tower — will be lit blue April 2 in honor of World Autism Awareness Day.

The buildings will go blue as part of a campaign by Autism Speaks to honor an annual international awareness day established by the United Nations in 2007.

Buildings that are expected to be lit blue include the Empire State Building and the New York Stock Exchange in New York, the Willis Tower — previously known as the Sears Tower — in Chicago, the CN tower in Toronto and the Kingdom Tower in Riyadh, Saudi Arabia.

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In addition, Autism Speaks is asking Web sites and bloggers to feature a blue color scheme to honor autism. And, retailers including Toys”R”Us, Lord & Taylor and Saks Fifth Avenue will be promoting autism awareness within their stores.

Beyond the events promoted by Autism Speaks, advocacy groups around the world are scheduled to host a series of walks and other awareness events April 2.