Illustration depicting the construction of the great church of Bern. Blocks of stone have been rough hewn before being transported to the building site. They are being raised by means of a lewis, an instrument from Operative Masonry. It is an iron cramp that is inserted into a cavity prepared for that purpose so that large stones may be raised to any height by rope and pulley. The stone is then placed in its proper position. At the builders feet are the tools of stonecutters including sledgehammers, dividers, and rulers. The Bern Minster is a Swiss Reformed cathedral, (or minster) in the old city of Bern, Switzerland. Built in the Gothic style, its construction started in 1421. Its tower, with a height of 330 feet, was only completed in 1893.