1700 (MDCC) was the year that began the 1700s decade. It is the 1700th year of the Common Era and Anno Domini, the 700th year of the second millennium, and the final year of the 17th century.
Calendars and leap years
Under the Gregorian calendar, 1700 was a common year that began on a Friday; the Gregorian rules exclude most century years from being leap years unless divisible by 400. In contrast, the Julian calendar treated 1700 as a leap year and therefore began on a Monday, because the Julian system adds a leap day every four years without exception.
At the start of 1700 the Gregorian calendar was ten days ahead of the Julian calendar. Because the Julian calendar included a February 29 in 1700 while the Gregorian did not, the difference between the two calendars increased by one day during 1700 and remained larger until the next skipped century leap day under the Gregorian system (in 1800), when it increased again.
The Swedish experiment
Sweden attempted an intermediate reform in 1700: authorities planned to move from the Julian to the Gregorian calendar gradually by omitting leap days over a 40-year period. As part of that plan, Sweden omitted the leap day in 1700, producing a national calendar that no longer coincided exactly with either the Julian or the Gregorian calendar. The experiment ran into administrative problems and was abandoned; Sweden reverted to the Julian calendar in 1712 (including the unusual addition of a February 30 that year) and later adopted the Gregorian calendar in 1753.