Historic Medford continues its series of 10 trolley tours highlighting the city's rich history. Learn about the Native Americans who lived here, the Mass Bay Colony with John Winthrop, the Mystic River, shipbuilding, bricks, rum, the transatlantic trade, the Royall House and Slave Quarters, the Middlesex Canal, Brooks Estate, Samuel Crocker Lawrence and the Lawrence Light Guard, and much more. The 90-minute tour begins and ends at the Salem Street Burying Ground on River Street. Tickets are $15 person (but…