1668 followed by 1669
1668 (MDCLXVIII) was a leap year starting on Sunday of the Gregorian calendar and a leap year starting on Wednesday of the Julian calendar, the 1668th year of the Common Era (CE) and Anno Domini (AD) designations, the 668th  year of the 2nd millennium, the 68th  year of the 17th century, and the  9th   year of the 1660s decade. As of the start of 1668, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.