Karlsplatz Stadtbahn Station in Vienna, Austria. Designed by Otto Wagner in 1899, now museum Stock Photo - Alamy
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VIENNA, AUSTRIA - NOVEMBER 6, 2019: Karlsplatz metro station sign of Vienna, Austria, also called U-Bahn indicating the lines U1, U2 and U4, seen from Stock Photo - Alamy
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File:Karlsplatz station U4, Vienna2008.jpg - Wikimedia Commons