1. Celebrate May Day: Revolutionary Revelry begins this afternoon with a May Day Celebration from 4 to 7 p.m. at Depot Square in Lexington Center. Enjoy May Day with a traditional dance around the Maypole; make your own May Day basket, get your face painted and more.

2. Today in Public Meetings: According to the town website, public meetings posted for today include the Education Collaborative for Greater Boston at 1 p.m. at the EDCO offices in Waltham and the Appropriation Committee at 7:30 p.m. at the Town Office Building. 

3. Today in High School Sports: Whole lot of athletic action for Lexington High teams this afternoon, including boys varsity tennis at 3:30 p.m. at Winchester High; girls varsity tennis at home vs. Winchester; boys varsity and JV baseball and girls varsity and JV softball at 3:45 p.m. at Wakefield Memorial High School; freshmen boys baseball vs. Wakefield at 3:45 p.m.; coed varsity Ultimate Frisbee at 3:45 p.m. at Phillips Academy and boys varsity and JV lacrosse at 4 p.m. at home against Billerica.

4. On This Day in History: In 1704, the Boston Newsletter published its first ad; in 1867, Reconstruction of the South began; in 1901, the Detroit Tigers committed 12 hours in a game against the Chicago White Sox; in 1939, Batman comics hit the street; in 1952, Mr. Potato Head was introduced; and, in 2011, President Obama announced Osama bin Laden had been killed by American military operatives.

5. Could be Cold and Rainy: Possible showers in the forecast before 2 p.m. and highs are only expected to hit the low 50s, according to the National Weather Service, which predicts a chance of a drizzle and patchy fog overnight with a low of 43.