Richard Thomas works at dizzying heights atop the ancient cathedral of Basel, and is master of one of the oldest crafts known to man – stonemasonry.
His job is to restore or replace decaying sandstones forming part of the Martin tower, which dates back to the 16th century.
Five hundred years on, the facades are under attack from the elements and acid rain, which causes the sandstone to disintegrate.
Hundreds of cracks have appeared in the ancient edifice, partly due to the use of poor quality replacement stones in the 1920s and 1960s, and the incorrect placement of stones.
The craftsmen working on the cathedral restoration project face a twice daily stomach-churning trip by open-air elevator to the 65-metre-high summit of the Martin tower.
As the lift lurches heavenwards, pedestrians resemble tiny specks on the cathedral square.
A sea of medieval rooftops spreads out below, and trams look like children’s toys wending their way through the cobbled streets.
As the elevator reaches the top of the tower, the snaking River Rhine comes into view on the other side, set against the backdrop of the Jura mountains.
Richard Thomas and his colleagues are not afraid of heights, but they are never allowed to forget the risks associated with such a panorama.
The site hut is protected by tiers of sturdy scaffolding, wrapped around the tower.
The platforms are covered in nets, like spiders’ webs, helping to protect the workers and to prevent unsecured tools or masonry falling from the tower.
Thomas works with three other stonemasons, the head of the site office, and an apprentice, whom he is currently training.
The Frenchman spent a year restoring Strasbourg Cathedral, and has been chief foreman at the Basel building site for the past three years.
The philosophy is to preserve the 500-year-old stones where possible, rather than replace them.
The stones are sanded down, and cracks are filled and sealed with chemicals and minerals.
If the sandstones are beyond rescue, the masons travel to Germany to handpick replacements from a quarry.
“You need a good eye for a top quality stone,” Thomas points out.
Copies of the original stones are faithfully reproduced, based on sketches drawn up by the craftsmen.
Thomas says there are drawbacks to the preservation philosophy: “A high quality new stone should last 70 to 80 years. But using all our modern restoration techniques, we can only prolong the life of an old stone by up to 30 years. Then we have to come back and work on it again.”
The tower top restoration is carried out in the warmer, summer months. In the winter, stones are fashioned in the workshop.
Stonemasonry is time consuming and precise, requiring deep reserves of patience.
Even using modern tools, carving a single block can take up to three weeks.
The skills of the craft have been passed on from master to apprentice since the Middle Ages, and the modern practitioners say they are proud to keep the traditions alive.
Thomas is fascinated by the history of the cathedral, which was extensively rebuilt in the Gothic style following a devastating earthquake in 1356.
Stonemasons who accompanied knights on the medieval crusades were inspired by the geometric forms used by Arab architects in Nicosia.
Returning to the west, they incorporated these forms in their own work, giving birth to a new Gothic movement.
The aim was to span in stone ever-wider surfaces from ever-greater heights.
Hans von Nussdorf was a widely respected German master of the Gothic form, and the architect of the Martin tower constructed between 1489 and 1500.
“We feel very close to the people who built this cathedral – we are their successors,” says Thomas.
“The work of renovating the cathedral is one of great passion.”
Thanks to the commitment of craftsmen like Thomas, the work of Hans von Nussdorf will be preserved for generations to come.
swissinfo, Julie Hunt in Basel
Richard Thomas practices one of the oldest and most dangerous professions known to man – his job is to restore ancient cathedrals.
The stonemason showed swissinfo around the building site at the top of the Martin tower of Basel Cathedral.
Remains of the first Basel Cathedral date back to the 8th century.
The building was destroyed in 917 when the Hungarians sacked Basel.
In the 11th century, Emperor Henry II endowed a new cathedral.
This was replaced by a Late Romanesque building a century later.
Five towers were destroyed by an earthquake in 1356.
The cathedral was restored in the Gothic style.