During her time in Poland, however, she visited a much more somber site - the Auschwitz-Birkenau State Museum in Kraków. The museum includes the sites of the Auschwitz I and Auschwitz II-Birkenau concentration camps where more than one million people were killed during the Holocaust.
While she was there, she shared this appropriately gloomy photo with a touching caption.
"My heart was heavy today," she wrote. She then shared the words the are written on a plaque hanging on one of the museum walls, "For ever let this place be a cry of despair and a warning to humanity, where the Nazi murdered about one and a half million men, women and children mainly Jews from various countries of Europe. Auschwitz - Birkenau 1940-1945 ."
She then concluded with this powerful quote, "'The one that does not remember history is bound to live through it again' George Santayana."
Katy has now left Poland and is currently in Vienna for her next tour stop.
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Gallery | What to Expect from Taylor, Katy, Miley and More in 2015