[Skybird]

Originally Posted by Letum

Likewise, the alternative explanation could be true, but I see the font
explanation as by far the most simple. We know such fonts where in use.

Do you have a source for the "who was confirmed by several surviving witnesses" bit?

What I said:

http://de.wikipedia.org/wiki/Arbeit_macht_frei

Am Tor des Stammlagers Auschwitz befindet sich der Schriftzug „Arbeit macht frei“ mit einem auf dem Kopf stehenden Buchstaben B. Ehemalige Auschwitz-Häftlinge berichten, es habe sich um einen heimlichen Protest ihres Mitgefangenen Jan Liwacz gehandelt, der als Kunstschlosser mehrere Auftragsarbeiten für die SS ausführen musste.

Edit:

the English wikipedia entry also mentions it:

the sign was made in 1940 by Polish political prisoners headed by Jan Liwacz (camp number 1010).[1] The upper bowl in the "B" in "ARBEIT" is wider than the lower bowl, appearing to some as upside-down. Allegedly it was made on purpose by political prisoners to make a signal what is really going on in Auschwitz.