The Masons of Djenné: a thousand-year-old craft that keeps a monument standing by hand.

In the heart of Mali, the world’s largest mud-brick structure survives thanks to an age-old tradition carried out every year by a guild of hereditary masons. The Barey-Ton masters carry on an unparalleled craft: building and rebuilding with mud, straw and shea butter. However, due to climate change, insecurity and modern materials, this expertise, which is listed as endangered world heritage, could die out with the current generation.

A colossus of earth that refuses to die

Traditional adobe bricks; Shutterstock

Towering over the city like a living sculpture, it is both massive and fragile. Located in the Inner Niger Delta, the Great Mosque of Djenné is the largest adobe building ever constructed. Its three minarets rise to a height of twenty metres, its walls enclose a space capable of holding a thousand worshippers, and its silhouette, bristling with protruding wooden beams known as torons, has become one of the most recognisable symbols of sub-Saharan Africa. First built in the 13th century by King Koy Komboro after he converted to Islam, the current mosque dates from 1907. Its reconstruction was overseen by Ismaïla Traoré, head of the Djenné masons’ guild. Together with the town and its archaeological sites, the mosque has been listed as a UNESCO World Heritage Site since 1988.

Barey-Ton, a corporation unlike any other

The Great Mosque of Djenné ; Jean-Louis Potier ; Flickr

Becoming a mason in Djenné is not something that happens overnight. This skill is passed down through the generations within the Barey-Ton, the guild of traditional builders. They are the masters of the proportions of the banco, a protective coating whose recipe is far from simple: the clay is taken from the Bani, a tributary of the Niger, and then mixed with water and natural additives such as rice bran, shea butter, and baobab powder. The bricks themselves, known as djenné-férey, are made from raw earth bound with bourgou grass and millet straw. This mixture is designed to withstand temperature fluctuations between day and night, thereby limiting the cracks caused by the sun. This is not merely a construction technique; it is an empirical science, refined over centuries, that only Barey-Ton members know how to implement fully.

Plastering: a building project that has become a communal ritual

Djenné ; Devriese ; Wikimedia

Every year, at the end of the dry season and before the rains arrive, Djenné is transformed into a vast open-air building site. The whole town comes together for the annual whitewashing of the mosque: the men climb the façades using torons, the projecting beams that serve as both decoration and permanent scaffolding; the women collect water; and the young people prepare the mortar. The master masons of Barey-Ton oversee the entire process, directing the work and adjusting the mortar mixtures. The day is accompanied by music and shared meals. This is much more than a technical maintenance task; it is an act of transmission. The youngest people learn the trade through practical experience, and the community reaffirms its connection to a heritage that it collectively upholds. In 2025, despite the challenging security situation, the plastering once again brought the community together just before the June rains.

Expertise caught in a vice

Ralf Steinberger ; Wikimedia

Since 2016, the ancient city of Djenné has been included on the List of World Heritage in Danger. The threats are numerous and interrelated. Climate change is reducing the availability of the high-quality clay required for banco construction, prompting some residents to switch to cement and fired bricks. The introduction of these modern materials, such as metal doors and standardised windows, is gradually altering the appearance and structural integrity of the town’s approximately two thousand traditional houses. Insecurity linked to conflicts in central Mali complicates access to the site and hinders conservation efforts. Then there is a quieter threat: if younger generations turn away from the traditional masonry trade due to insufficient economic opportunities, Barey-Ton’s heritage could be lost within a generation.

Save the walls, save the hands

14-03-14-UNESCO in Timbuktu 15 ; Flickr

For several years, UNESCO and its partners, including the Aga Khan Trust for Culture, have supported conservation efforts. Since 2009, structural consolidation work has been carried out, bringing together international experts and masons from Barey-Ton in an approach that transforms the site into an ongoing training facility. The challenge extends beyond merely preserving a monument; it is about maintaining a living ecosystem of skills. In Djenné, the building and the builder are inseparable. The mosque is not a static object that can be restored once and for all — it is a form of architecture that requires constant renewal by those who understand its intricacies. Protecting Djenné means protecting a craft. And to protect this craft is to embrace the notion that certain forms of knowledge survive only through practice.