What does hell smell like? AI recreates scents that shaped European history and culture.

What do you think hell smells like? British researcher William Tullett has faithfully recreated that stench , or at least the way our ancestors imagined it. Thanks to an EU-funded research initiative carried out between 2021 and 2023, Tullett didn't have to spend years searching for archives across Europe. Instead, he was able to access this information using ODEUROPA Smell Explorer , a unique and intuitive database of historical smells that compiles more than 2.4 million instances or specific mentions of different odors.

“Hell and its symbolism play a very important role in European and Christian culture,” says Dr. Tullett, an expert in olfactory history and senior lecturer at the University of York (UK). To reconstruct this particular scent, he gathered important references from 16th and 17th-century sermons, ranging from the expected smell of sulfur to more evocative descriptions, such as “a million dead dogs.”

This infernal odor was just one of a dozen historical scents presented at the European Pavilion at the 2025 World Expo in Osaka, Japan. Other scents portrayed included frankincense, myrrh, and the Amsterdam canals, each with its own emotional, cultural, and historical connotations. All were recreated by the ODEUROPA research team.

Professor Inger Leemans , a cultural historian at the Free University of Amsterdam (Netherlands) and coordinator of the research team, comments that the World Expo was a vivid example of how subjective and relative smells are in historical context. According to Leemans, while some Europeans, strangely, found the smell of hell appealing, as the smoky aroma reminded them of roasted meat, Japanese visitors to Osaka found it “absolutely repugnant.”

Preserving the olfactory heritage

Olfactory heritage, that is, the set of smells with cultural or social value, remains underexplored and difficult to document. Although research on smell as a cultural phenomenon has been attracting increased interest for some time, the work has been divided among several disciplines.

“This project has allowed us to bring together knowledge about smells from various fields, including history, art history, chemistry, and heritage science,” Leemans notes, referring to the work carried out by researchers from Germany, Slovenia, France, Italy, the Netherlands, and the United Kingdom, which went far beyond recreating the sulfurous smell of hell. The ODEUROPA team has developed an olfactory heritage toolkit with a list of olfactory practices, odors, and “aromatic places.”

Its purpose is to help heritage researchers and policymakers recognize and safeguard significant odors and olfactory landscapes—smells or aromas that characterize a particular place, environment, or time.

From a practical perspective, Tullett comments, smell can be a powerful tool to help people connect with history. Museums and historical sites could use scents to make exhibitions more immersive and memorable. “Smell allows us to establish a more tangible, authentic, and real relationship with the past,” he notes.

Museums and historical sites are already paying attention to this topic, and exhibition curators are increasingly turning to smell as a means of engaging their visitors. For example, the ODEUROPA team helped create an olfactory tour of the Ulm Museum (Germany), a space dedicated to art, archaeology, and urban and cultural history.

They also developed a self-guided city tour of Amsterdam , with scratch-and-sniff maps and an olfactory storytelling toolkit that offers practical guidance for working with scents in museums and historic sites.

To uncover historical insights and “stories experienced through smell” from some 43,000 images and approximately 167,000 historical texts in six languages, the researchers trained artificial intelligence (AI) models to find references to smells and aromas in texts and images from the 16th to the early 20th centuries.

Building on this foundation, they created knowledge graphs—structured networks of interconnected information that link data and contextualize it. This advanced use of AI supports the EU's growing ambition to make cultural heritage more relevant and accessible, including through Europeana , the European platform for digitized cultural content.

Inspiration comes from Japan

Even before the World Expo, ODEUROPA researchers were already exchanging ideas with their Japanese counterparts and drawing inspiration from that country's pioneering work in the field of scent preservation. "Japan has been a source of inspiration in the conception of smell as a heritage entity," says Leemans.

In 2001, Japan's Ministry of the Environment compiled a list of the country's 100 most remarkable olfactory landscapes, from the sea mist that envelops the Kushiro region in cool summers to the white peaches of the Kibi Hills or the scent of Korean cooking in Osaka's Tsuruhashi district.

All of this encouraged the ODEUROPA team to reflect more broadly on olfactory landscapes and how they convey identity, spaces, and memory. “Olfactory landscapes are important spaces that must be protected and that have a particular value,” says Leemans.

Smell once held a much more important place in Japanese culture, according to Maki Ueda , a pioneering Japanese olfactory artist whose work also served as inspiration for the European team. As Ueda explains, during the Heian Period, over a thousand years ago, scents were not only fragrances but also a social code of communication and information. “Today, this delicacy and sensitivity toward scents has been lost.”

Ueda emphasizes that connecting with olfactory art is a meaningful experience with educational value: “People realize they’ve forgotten how powerful the sense of smell can be.”

Connect with the forgotten sense

Leemans agrees that smell is an unfairly overlooked sense, but believes it could regain relevance. “Most people have a wealth of olfactory knowledge that they don't normally use much. They may not be able to put it into words, but if we give them a hand, they could make sense of all that knowledge,” he comments.

To keep this olfactory dialogue alive, Leemans left his AI avatar in Osaka. Its digital version will continue to present ODEUROPA's research and answer visitor questions for the remainder of the World Expo.

His team also discussed future collaborations with Japanese partners who are doing interesting work on collecting, documenting, and presenting scents. “There are countless ways we can move forward together and learn from each other,” says Leemans.

The research described in this article was supported by funding from the EU's Horizon Programme. The views of those interviewed do not necessarily reflect those of the European Commission.

Article originally published in Horizon , the European Union's research and innovation magazine.