The title of the post says it all.  A collector, Erik Voskuil, has posted on his blog, beforemario.com, about a very old piece of Nintendo memorabilia in his collection.  This piece of Nintendo history is priceless and possibly one of the only pieces of its kind left in existence.

The small promotional calendar, pictured below, is a hundred years old and was used to promote Nintendo during the early days of their existence as a card making company.  The front of the card shows information about the company and the back displays a calendar.  More detailed information about the calendar can be found at beforemario.com.

Source: beforemario.com via Kotaku