Millennia Calendar displays date and time for any locations on the Earth; includes 12 traditional and modern calendars (Julian, Byzantine, Gregorian, Indian, Ancient Egyptian, Coptic, Ethiopian, Hebrew, Islamic, Khayam, Persian, Slavic-Aryan); spans over a period of 8.5 thousand years (7.5 thousand years into the past and 1 thousand years into the future); takes into account the fact that in some calendars (Hebrew, Islamic etc.) new date begins either at sunset or sunrise; displays holidays and memorial days of many countries and religions: Christianity (Orthodoxy and Catholicism), Judaism, Islam (Shia and Sunni) and Ingleaism; allows historical and astronomical years counting; displays time of rise, transit and set of the Sun, the Moon and Planets; displays dates of equinoxes and solstices; displays dates and types of solar and lunar eclipses; displays horizontal coordinates of the Sun, the Moon and Planets; allows to save calendar and the list of holidays to HTML document; allows to saves the list of astronomical events to HTML or CSV document. Most of the astronomical calculations use algorithms set forth in the book `Astronomical Algorithms` by Jean Meeus. Accuracy of these calculations is sufficient for the demonstration of correlation of astronomic events and calendars.