How much more difficult? As historian Michele Renee Salzman remarked in "The Cambridge Companion to Ancient Rome," the calendar was so far out of whack by Caesar's time that in 44 B.C., Jan. 1 ...

Feb. 29 is more than just an extra day we have once every four years. There is some science behind it. Here's how leap days ...

The ancient Egyptian calendar consisted of 365 days without ... the festival occurred at different times of the year. During the Roman occupation of Egypt from the mid-1st to mid-3rd centuries ...