With origins dating to the mid-19th century, California’s largest town square is a grassy plaza with four identical sides to give equal importance to all its merchants. Today it’s home to festivals and a weekly farmer’s market, popular for its shops, restaurants, tasting rooms, galleries, a historic inn and vintage cinema. In the middle, Sonoma City Hall is a handsome 1908 Italianate structure. Highlights for history buffs: General Vallejo’s headquarters and Mission San Francisco Solano de Sonoma, northernmost Franciscan outpost. Don’t miss: Bear Flag Monument, a registered landmark where California’s flag was first raised to mark independence from Mexico in 1846. parks.ca.gov/sonomashp/<