1671 was a common year starting on Thursday of the Gregorian calendar and a common year starting on Sunday of the Julian calendar, the 1671st year of the Common Era (CE) and Anno Domini (AD) designations, the 671st year of the 2nd millennium, the 71st year of the 17th century, and the 2nd year of the 1670s decade. As of the start of 1671, the ...