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 7 thousand years (4 thousand years into the past and 3 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.