This is not only the oldest accurate calendar ever recorded, it is the by far the longest period of continuous use.

His calendar is in fact the most accurate calendar in the world today.

The second component consisted of an approximation which would provide an accurate yet simple, rule-based calendar.

It inaugurates the most accurate solar calendar known to the ancient world, with 365 days per year.

The Aztecs had an extremely accurate calendar which consisted of 365 days.

But counting sleep periods was not an accurate calendar.

The task before the Committee was to prepare an accurate calendar based on scientific study, which could be adopted uniformly throughout India.

This produced a noticeably more accurate calendar, but it was based on a length for the year of 365 days and 6 hours (365.25 d).

They kept accurate official calendars and were public servants.

How did the Maya create such stunningly precise calendars, still accurate today?