Luxembourg - P-55a in Envelope - 1972 dated Foreign Paper Money

50 Francs, P-55a. Security strip! Note in large envelope "Banknotes of all Nations". The Luxembourg franc was the currency of Luxembourg between 1854 and 2002, except from 1941 to 1944. From 1944 to 2002, its value was equal to that of the Belgian franc. The franc remained in circulation until 2002, when it was replaced by the euro.

The conquest of most of western Europe by Revolutionary and Napoleonic France led to the French franc's wide circulation, including in Luxembourg. However, incorporation into the Netherlands in 1815 resulted in the Dutch guilder becoming Luxembourg's currency. Following Belgium's independence from the Netherlands, the Belgian franc was adopted in 1839 and circulated in Luxembourg until 1842 and again from 1848. Between 1842 and 1848, Luxembourg (as part of the German Zollverein) used the Prussian Thaler. Read more at https://en.wikipedia.org/wiki/Luxembourg_franc