Sofiensaal (or Sofiensäle) is the name of a former public bath and concert venue in Vienna. It was built as a public bath in the years 1845-1848 by Eduard van der Nüll and August Sicard von Sicardsburg. It was used as a bath in winter. During the summer, the swimming pool was covered with wooden planks. The venue could then be used for concerts, and as a dance venue. In March 1912 Karl May gave his last public speech there. He had an audience of about 2000 people. In September 1913, the first movies that had sound were shown in the building. This was later stopped however, as there were problems with making sure the sound was at the right time in the movie (called synchronicity).