The West Side Market may be celebrating its 100th birthday in November, but we don’t think it looks a day over 70. Nonetheless, the centennial festivities kick off today at 5:30 p.m. and are set to last all year. (And we thought we knew how to par-tay!) The market, which is now home to more than 100 vendors attracting more than 1 million visitors a year, has a venerable history. Leave it to manager Christine Eadie to put it in perspective: “It’s been selling food longer than we’ve had refrigerators!” So it’s only fair that today’s partygoers can chill at a ribbon-cutting ceremony for the newly opened Market Square Park, and enjoy multi-ethnic music and dance performances representative of all the city’s assorted cultures. Also on tap: a cool ice-cream social with free Mitchell’s Homemade treats for the first 3,000 visitors. You’ll want to make sure you stick around for the evening’s, ahem, explosive ending too: fireworks! “The West Side Market is not just a place to get groceries,” Eadie reminds us. “It’s a place of community, too.” Admission is free. See the website for details.