1604

1604 (MDCIV) was a leap year starting on Thursday of the Gregorian calendar and a leap year starting on Sunday of the Julian calendar, the 1604th year of the Common Era (CE) and Anno Domini (AD) designations, the 604th year of the 2nd millennium, the 4th year of the 17th century, and the 5th year of the 1600s decade. As of the start of 1604, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.