Saturday 9/9: Walking tour and celebration of the Somerville Community Preservation Act, starting in East Somerville at 12:30 pm, continuing through Union Square, ending at the Prospect Hill Tower at 2:30 pm.
Saturday 9/9 (with some activities on Friday and Sunday): Assembly Row Riverfest, including fireworks over the Mystic River Saturday night.
Friday-Sunday, 9/8-10: Greek Food and Music Festival at Dormition Church, 29 Central Street.
Friday-Sunday, 9/8-10: Italian Festival of the Healing Saints Cosmas and Damian, on Warren Street at the Cambridge-Somerville line, near Twin City Plaza.
Sunday 9/10: Rock & Roll Yard Sale in Union Square.
Sunday 9/10: Cambridge Caribbean Carnival, parade followed by festival in Kendall Square.
Sunday 9/10: Somerville Dog Festival at Trum Field.