The man who inspired the ice bucket challenge that has raised millions for ALS research is being honored at Boston City Hall. Mayor Martin Walsh is hosting a rally Tuesday for Pete Frates at City Hall Plaza. The event coincides with the release of a new book on Frates. "The Ice Bucket Challenge: Pete Frates and the Fight against ALS" was written by Casey Sherman and Dave Wedge. Half of its proceeds benefit the Frates family. Walsh will declare Sept. 5 as Pete Frates Day in Boston. Frates, his family, the book authors, Boston Red Sox officials and the Boston College baseball team are expected to attend. Frates is a former Boston College baseball star who has inspired millions of dollars in donations for research on amyotrophic lateral sclerosis or ALS.