Sheshach

Sheshach - (Jer. 25:26), supposed to be equivalent to Babel (Babylon),
according to a secret mode of writing among the
Jews of unknown antiquity, which consisted in substituting the
last letter of the Hebrew alphabet for the first, the last but
one for the second, and so on. Thus the letters sh, sh, ch become b, b, l, i.e., Babel (see: Atbash cipher).This code is called the Atbash Cipher and was used to decrypt. The city does not appear on any map nor in any other documents, save the book of Jeremiah. The Atbash Cipher was applied and out of Sheshach came the word Babel. This is supposed to be confirmed by
a reference to Jer. 51:41, where Sheshach and Babylon are in
parallel clauses. There seems to be no reason to doubt that
Babylon is here intended by this name. (See Streane's Jeremiah,
l.c.)
Category:Hebrew Bible places