The largest bell of the St. Stephen's Cathedral is officially named for St. Mary, but usually called Pummerin ("Boomer") and hangs in the north tower.
The Old Pummerin was originally cast in 1705 from 208 of the 300 cannon captured from the Muslim invaders in the Second Turkish Siege of Vienna. It had a diameter of 3,16 meters (2 centimetres more than the New Pummerin), with a pitch of B (a half-tone lower than the New Pummerin).
The Old Pummerin last sounded on Easter 1937. A fire caused by war-time looters of near-by shops destroyed the bell when its wooden cradle burned through and the bell crashed onto the stone floor of the south tower on 12 April 12 1945.
The new Pummerin (officially Marienglocke, named for St. Mary) was a gift from the province of Upper Austria and was cast on 5 September 1951 in St. Florian, Upper Austria from the Old Pummerin's metal (supplemented by metal from some of the remaining captured Turkish cannons at Vienna's Heeresgeschichtliches Museum). At 20.130 kg (44.380 lb), without the clapper weighs of 813 kg, the new Pummerin is the largest bell in Austria and the third largest swinging bell in Europe after the 23.500 kg (51.810 lb) Peter in Cologne Cathedral (Germany) and the 22.700 kg Maria Dolens in Rovereto (Italy). The new bell has a diameter of 3,14 meters (10 ft 4 in) and a height of 2,94 meters. The bell bears three reliefs showing the Blessed Virgin as the Immaculate Conception, a scene from the Ottoman siege of Vienna (1683), and a scene of the conflagration in 1945. Like the Old Pummerin, the heads of Turks adorn the brackets at the top, and an interlocking square chain design decorates the bottom rim. It arrived in Vienna on 26 April 1952 and was consecrated by Cardinal Theodor Innitzer that same day. It rang for the first time the next day at a Pontifical High Mass, but from the cathedral's building yard where it remained until its new home was completed. The cathedral authorities wanted the main bell to again be a traditional swinging bell, so it was decided to design the new bell this way, and (because its old home in the south tower had already been proven too vulnerable) to hang it in the shorter, but sturdier, north tower (Nordturm). Repair of the landmark south tower (Südturm or better known as "Steffl") had been given higher priority, so the north tower was not ready to receive its new tenant until five years later. The new Pummerin was driven through the Giant's Door on the west front and installed on a steel structure within the north tower on 5 October 1957. The Pummerin sounds on only a few special occasions such as high Catholic holidays such as Easter, Whitsunday, Feast of Corpus Christi (Pentecost), Christmas Eve, and St. Stephen's Day, but also at state funerals and at the beginning of the New Year. On All Souls' Day (2 November) it rings to commemorate the fallen in World War II. On the 23rd of April it rings to celebrate the religious dedication of St. Stephens. To minimize excess vibrations of the supporting structure, since 2003 the bell's electrical swinging mechanism has been carefully controlled by a computer.