One morning, Helder — my project partner in Portugal — sent me two screenshots and almost nothing else. The first was a photograph of glass grave lamps glowing in a Porto cemetery, and across it a single question: what to do if bodies don't decompose?

The text beneath it explained. Portuguese cities had run out of burial land. Since the 1960s, most people are buried not in a plot they keep but in a temporary grave, leased for three years; then it is opened, the bones are moved to a small box in a wall, and the ground passes to the next family. It is a city that recycles its dead because it has no room to do otherwise. But in Porto, Helder's screenshots said, half of those graves are opened too early — the body still there, and a growing number not decomposed at all. They had dried into mummies. And the law offered no way out: if soft tissue remains, the grave is simply covered again, for two-year cycles, with no limit on how often that repeats.

Helder was not sending me a ghost story. He was sending a design brief. In our work on Sim Eternal City we go looking for the exact point where a city's systems quietly break — and here was one, wearing the face of the uncanny: a burial machine that had jammed on the one thing it never planned for, a body that refuses to leave. This is our answer to his question.

Between 2006 and 2015, an estimated 55–64% of first-time exhumations in Porto revealed bodies that were not fully decomposed. This should not happen on the wet Atlantic coast; spontaneous mummification belongs to deserts and glaciers. The forensic anthropologist Ângela Silva-Bessa of the University of Coimbra has sampled graves across five cities and documented families forced into a fourth reburial of the same person.

The cause is still unknown. Silva-Bessa tested eight soil properties and found no correlation — two graves side by side, same soil, one clean bone and one intact body. Suspicion has moved from the ground to the person: medication and smoking in the final years of life. Nothing is proven. And the law allows no shortcut: if soft tissue remains, the grave is covered again for successive two-year cycles, with no limit on how often that repeats.

Every current answer shares one assumption: that the body must decompose on the city's timetable. The national reburial rule simply tries again, indefinitely. Braga and Peso da Régua now require decomposition-accelerant material inside the coffin before it is closed. Other cemeteries build locais de consumpção aeróbia — aerobic chambers that feed oxygen to the body through separate ventilation and drainage lines. Research at Coimbra found decomposition inside them also runs slow.

They fail for the same reason: you cannot engineer a fix for a mechanism no one has yet identified.

The No Stone Tombstone answer abandons the war on the corpse. It makes the biological outcome irrelevant.

One decision solves three problems at once: the mummification jam, the shortage of land, and — as we'll see — the religious requirement that remains rest in a sacred place. To make it dignified rather than merely efficient, two systems fuse: a machine below, and a memory layer above.

Japan already treats its cremated dead the way it treats its inventory. In an automated columbarium, a family taps an IC card and a robotic stacker crane retrieves their urn from a high-density underground rack and delivers it to a private booth; when the visit ends, it files itself away again. Racks reach twenty metres and hold thousands, at roughly a third of the cost of a traditional plot.

The Shinjuku Rurikoin Byakurengedo (2014) holds about 7,000 urns on a Toyota Industries system; Kōkoku-ji's Ruriden lights one of 2,046 crystal Buddhas to the visitor's card; conveyor-fed columbaria have spread from Aichi since 2016. The suppliers are Daifuku and Toyota Industries — warehouse robotics, adapted for the dead. In our adaptation, the entire vault is consecrated as one sacred sanctuary.

A tombstone claims land forever. A media pole claims nothing new. The No Stone Tombstone hypothesis, first drawn for New York's LinkNYC network, is that the city's existing street infrastructure can carry the dead. A family authenticates at the nearest pole; the vault below identifies their urn; and for a few minutes the pole becomes a private memorial — portrait, voice, a digital candle. Then it returns to being a civic screen: light, information, communications. Memory occupies time, not land.

The three-year term ends in a choice. The fire path is flame cremation: fast, symbolic, and permitted by the Catholic Church since 1963. The water path is alkaline hydrolysis — aquamation — which dissolves soft tissue in heated alkaline water at a fraction of the energy and carbon of flame, leaving bone to return as ash and a sterile, nutrient-rich liquid.

The difference is where the story ends. Fire ends in the vault. Water ends in the vault and in the city's metabolism — its liquid routed into an energy and water loop, making the No Stone Tombstone the literal fulfilment of Sim Eternal City's aim to fold the traces of the dead back into the systems of the living.

The vault is designed for a Catholic city. Because every urn rests in a single consecrated sanctuary, the system satisfies the Church's principle that remains be kept in a sacred physical place. Aquamation is harder: in 2023 the U.S. bishops judged water cremation as not adequately respecting the body, largely because its liquid is discharged to waste. The design answers this head-on — the fire path stays the Catholic-compatible default, while the water path reroutes its liquid into a consecrated loop rather than a sewer. Two endings, one sanctuary, room for a city, a family, and a faith to each choose.

The shortage is not a Portuguese quirk; it is the European baseline. London has reused graves since 2007, lifting and deepening plots older than seventy-five years. Berlin leases graves for twenty or thirty years and then reuses them. Athens runs a three-year cycle almost identical to Portugal's — lease, exhume, move the bones to an ossuary. Paris, Rome and Naples are pressed to the same edge. Every one of these systems rests on the same quiet assumption: that the body decomposes on schedule. Porto simply stands in the front row, at the point where that assumption fails — which is exactly why a solution proven there would travel.

And the second layer — the media pole — is no more hypothetical than the first. London already runs BT's Street Hubs, the direct descendant of LinkNYC from the same maker; Paris has JCDecaux's digital street furniture, Berlin has Ströer's digital columns, Amsterdam its smart-city kiosks, and 5G smart-poles are arriving city by city. No Stone Tombstone does not need LinkNYC specifically — it needs a networked civic pole, and those already stand on these streets. Better still, its Memorial Mode carries no advertising, which fits the very cities — Paris, London — that keep pushing street-ad screens back.

Porto's problem is among the strangest a city can face: bodies that will not decompose, clogging a system built to keep moving. The answer is not a better chemical or a bigger cemetery, but a redesign of the relationship between the body, the land, and memory. Japan supplies the sacred machine below. New York supplies the memory layer above. Porto supplies the reason the world will believe it is necessary.