Cologne Cathedral

For roughly four hundred years the most famous thing about Cologne Cathedral was a crane. Building work had stopped around 1560 with the choir finished, a fragment of nave standing, and the south tower risen to about a third of its intended height. On top of that stump the masons left their great timber treadwheel crane in place, ready for the next block. The next block never came. The crane stayed up there through the Reformation, the Thirty Years' War, Napoleon's occupation, long enough to appear in almost every engraving of the city as its accidental emblem. Cologne's skyline, for most of its modern history, was a monument to something unfinished.

Three Kings In A Golden Box

The reason the cathedral exists at all is a set of bones. In 1164 the Holy Roman Emperor Frederick Barbarossa took Milan and handed its most prized relics to Rainald von Dassel, the Archbishop of Cologne: the remains venerated as those of the Magi, the three kings of the Nativity story. Over the following decades the goldsmith Nicholas of Verdun and his successors built them a reliquary the size of a small chapel, gilded and enamelled and studded with gems, the Shrine of the Three Kings. Pilgrims came in enormous numbers. The old cathedral, a building of the ninth century, was suddenly too small for its own contents.

On 15 August 1248 Archbishop Konrad von Hochstaden laid the foundation stone of a replacement designed to outdo the great French cathedrals of Amiens and Beauvais. The choir was consecrated in 1322 and the shrine moved inside. Then the pace slackened. Parts of the nave rose, the south tower grew its first storeys, and by the mid-sixteenth century the money, the will and perhaps the faith had run out. In a Germany convulsed by the Reformation, a vast Catholic building site was no one's priority.

The Drawing In The Attic

What restarted everything was a piece of parchment. In 1814 the architect Georg Moller found, in Darmstadt, one half of the original medieval elevation drawing of the cathedral's west front. The other half turned up in Paris two years later. Joined together, they showed for the first time what the thirteenth-century masons had actually intended: two towers with spires, each well over 150 metres. In the Germany of the Romantic era this was electrifying. The half-built cathedral looked like the half-built nation, and finishing it became a patriotic cause that Catholics and Protestants could share.

In 1842 King Frederick William IV of Prussia laid a second foundation stone, and this time the work did not stop. The plan was medieval, the means were not: iron roof trusses, steam power, stone delivered by rail. In the summer of 1880 the final finial was hoisted onto the south tower, and on 15 October, 632 years after the first stone, the building was declared complete in a ceremony attended by Kaiser Wilhelm I. At 157 metres it was the tallest structure in the world, a title it held for four years until the Washington Monument overtook it. The medieval crane was finally taken down.

The people of Cologne have a saying that the world will end when the cathedral is finished, and they have taken care to avoid the risk. The cathedral's own stonemasons' workshop, the Dombauhütte, has been in continuous operation since the Middle Ages, replacing weathered blocks one at a time. There is always scaffolding somewhere on the building.

Fourteen Bombs

The Second World War erased the centre of Cologne. The cathedral took fourteen direct hits from aerial bombs; the north tower was badly damaged, the windows shattered, one of the nave vaults collapsed. But the towers stood. In the photographs American soldiers took in 1945 they are the only upright thing in miles of rubble. It is often said that Allied pilots used the spires as a navigation landmark, and whatever the truth of that, the survival was nobody's plan. Repairs ran until 1956, and the brick patch on the north tower stayed visible for decades.

Inside are things older than the building. The Gero Cross, carved around 970, is the oldest surviving large crucifix north of the Alps; it was made for the previous cathedral and simply carried over. In the south tower hangs the Petersglocke, cast in 1923 and weighing about 24 tonnes, known locally as Dicker Pitter, "Fat Peter." And since 2007 the south transept has held a window designed by Gerhard Richter: 11,500 squares of coloured glass arranged at random, a pixel storm beside the medieval saints.

Today

The cathedral is the seat of the Archbishop of Cologne and one of Germany's most visited buildings. UNESCO listed it as World Heritage in 1996, put it on the endangered list in 2004 when high-rises were planned on the opposite bank of the Rhine, and removed it in 2006 once the plans were scaled back. The present enemy is air rather than bombs: a century of soot and sulphur has eaten the sandstone, and the masons keep swapping out what it has eaten. A building that waited four hundred years under a crane has now gone a hundred without being seen free of scaffolding. Perhaps the saying is right, and everyone is safer this way.