ToDate[time] converts an absolute time in seconds since the beginning of January 1, 1900 to a date of the form y, m, d, h, m, s.
ToDate converts between the forms returned by AbsoluteTime and Date.
ToDate assumes that both the absolute time and the date are to be given in the same time zone.
See The Mathematica Book: Section 2.13.3.
See also: FromDate.
Related package: Miscellaneous`Calendar`.