This is a very rare Altemus advertising cover from 1890. In 1889 Altemus published the six titles of the Dore’s Masterpieces Series. (http://henryaltemus.com/series/series78.htm). All six oversized volumes were published until 1903 in a number of different formats. Because of the beautiful Gustave Dore illustrations, these books are always in great demand and sell for a premium.
This advertising cover pictures Format 1- Volume 1 in the series. The other books are listed at the top of the envelope. Die Dore Bibel Gallerie is a German translation of Volume #1 and was included in this series beginning in 1892. (Thus, at that point there were seven titles in the series.)