Officially called the Cathedral Church of St Peter, the building is a renowned monument of German Catholicism. Although building began in 1248 it remained unfinished during medieval times, with work stopping in 1473. It was eventually completed in 1880. In the Twentieth century, although hit by many allied bombs, it remained standing unlike much of Cologne, which was flattened. In 2007, a stunning new ‘pixelated’, stained-glass window, by artist Gerhard Richter and made up of 11, 500 pieces of coloured glass all the same size, was installed. It is a UNESCO World Heritage Site.