The 24 sheet normally measures 246" x 
      108", and is used mostly for billboard advertising, although some are placed 
      on the sides of large buildings. They come in a number of pieces and are 
      placed together like a puzzle. Their artwork is designed to catch the attention 
      of motorists as they drive by. They are issued primarily for major motion 
      pictures. It got its name from the fact that it is approximately 24 times 
      the size of a one sheet.
    Here's a sample 24 sheet:
    
    HISTORY
    The world’s first 24 sheet was displayed 
      at the Paris Exposition of 1889 and the Columbian Exposition in Chicago 
      in 1893 by Morgan 
      Litho. 
    It was very quickly adopted for all types 
      of advertising, especially for the circus, and traveling shows.
    Movie studios began utilizing billboard 
      advertising around 1915. The use of this type of advertising occurred around 
      the same time that movies grew from two to five reels.
    Movie studios still issue billboard-size 
      paper in limited numbers, primarily as 24 sheets and 30 
      sheets.
    AS A COLLECTIBLE
    Very few 24 sheets are available in the 
      movie art collectors market. There are printed in limited numbers. Since 
      they are used outside, most of them are destroyed when they are removed 
      from the billboard. Thus, it is rare to find 24 sheet that is intact unless 
      it was never actually used on the billboard. There are very few collectors 
      who handle this size because it is so large. The 24 sheet has been used 
      as murials in clubs and large halls.
    For a list of images of 24 sheets in the 
      MoviePosterDataBase, click here