Construction of the Cathedral began as early as 1170 by an original unknown master mason. Twenty years later another master mason restarted construction until 1215. Finally a third engineer, Jean Cotereel, completed the majority of the existing cathedral including a porch, and two towers, one of which is the current day belfry. The other tower was never completed. The cathedral was consecrated and dedicated to Our Lady in 1275 by Pope Gregory X, Rudolph of Habsburg, and the bishop of Lausanne at the time, Guillaume of Champvent. The medieval architect Villard de Honnecourt drew the rose window of the south transept in his sketchbook in 1270. The Protestant Reformation, in particular the variant which came from nearby Geneva, significantly affected the Cathedral. In 1536 a new liturgical area was added to the nave and the colourful decorations inside the Cathedral were covered over. Other major restorations occurred later in the 18th and 19th century which were directed by the great French architect, Eugène-Emmanuel Viollet-le-Duc.During the 20th century major restorations occurred to restore the painted interior decorations as well as to restore a painted portal on the South side of the Cathedral. New organs were installed in 2003. The great pipe organ of the Cathedral of Notre Dame of Lausanne was inaugurated in December 2003. It is a unique instrument in the world. It took ten years to design it and it is composed of 7000 pipes, two consoles, five manuals, and one pedalboard. It is the first organ in the world to be designed by a designer. It is the first organ to contain all four of the principal organ styles (classical, French symphony, baroque, German romantique). It is also the first organ manufactured by an American company (Fisk) for a European Cathedral. It cost a total of 6 million Swiss francs, took 150,000 man-hours to build and weighs 40 tons. It was preceded by a Kuhn Organ from 1955 which has since been relocated to the Polish Baltic Philharmonic in Gdańsk, Poland. The organist is Jean-Christophe Geiser. The Cathedral has a total of seven bells that are suspended on two floors of the belfry.[7] The two biggest bells are located on the lower level while all the other bells are on the top level. The oldest bell dates back to 1493 while the most recent bells date back 1898.