The National Museum of Ethnology (Minpaku) is a research center for ethnology and cultural anthropology.

Ethnic Cultures Crossing Borders: People Moving, Cultures Mixing

Calendars are usually used to measure time in daily units.  These days add up to weeks and months and finally years.  There is a great variety of calendar systems in the world but the Gregorian Calendar is the world standard.  Still, one can find important national and religious holidays not only in the Christian calendar but in other calendars as well.