How Zurich's Digital Archives Ended Up Full of Identical Images — and What Happened Next

Zurich's municipal digital infrastructure is sitting on a problem that has been building quietly since at least 2018: thousands of duplicate images scattered across departmental servers, public-facing portals, and archival systems maintained by bodies ranging from Stadtarchiv Zürich on Alfred-Escher-Strasse to the communications offices at the Stadthaus on Stadthausquai. The city's IT coordination unit formally acknowledged the scale of the problem in a working document circulated among department heads in spring 2026, according to publicly available administrative records.

The timing matters. Switzerland's Federal Act on Data Protection, revised and in full force since September 2023, places stricter obligations on public bodies to maintain accurate, non-redundant records. Holding multiple untagged copies of the same image — some of which may contain personal data, faces, or location metadata — is no longer a minor housekeeping failure. It is a compliance issue with measurable legal exposure.

How the Duplication Problem Grew

The roots stretch back to the early 2010s, when individual city departments began digitising their holdings independently rather than through a unified platform. The Baugeschichtliches Archiv, housed in the same building complex as other city collections near Neumarkt, ran its own scanning and cataloguing workflow. The tourism promotion body Zürich Tourismus maintained a separate image library on a different content management system. The communications arm of the Stadtrat uploaded photographs to yet another server. Nobody was required to cross-reference before uploading, and no single authority held responsibility for deduplication.

By the time the city began migrating toward a unified content services framework — a process that formally started in 2022 as part of the broader Smart City Zürich programme — IT auditors discovered that storage volumes dedicated to image files had grown by roughly 340 percent over eight years, while the actual number of unique photographs was far lower than the file count suggested. That figure comes from internal planning documents referenced in the 2025 annual report of the city's Departement der Informatik, which is publicly accessible on the Stadt Zürich website.

ETH Zürich researchers working in the university's computer vision and digital preservation labs on Rämistrasse have been tracking this class of problem across European municipal archives for several years. Their published work, including a 2024 paper in the journal Digital Scholarship in the Humanities, found that mid-sized European cities with federated rather than centralised digital governance consistently accumulate duplicate image ratios that can reach three or four copies per unique asset within a decade. Zurich fits that profile precisely.

The Cost and What Comes Next

Storage costs in Swiss municipal cloud infrastructure are not trivial. Procurement data published by the Beschaffungskonferenz des Bundes shows that compliant, sovereignty-preserving cloud storage in Switzerland — the kind that keeps data onshore and satisfies cantonal data residency requirements — runs significantly higher per terabyte than equivalent services in the EU. Eliminating redundant image files is, in straightforward terms, a budget issue as much as an archival one.

The city's current plan, outlined in a Smart City Zürich roadmap update published in March 2026, calls for deploying automated deduplication tools across the three largest image repositories by the end of the third quarter of 2026. A joint working group involving the Stadtarchiv, the Amt für Städtebau on Lindenhofstrasse, and external technical consultants has been meeting monthly since February. The process will also include a manual review phase for any files flagged as potentially containing personal data, in direct response to the 2023 data protection revision.

For residents and businesses that rely on the city's open-data image portal — used by journalists, architects, urban planners and researchers — the practical consequence will be a cleaner, faster, better-tagged resource. The portal has drawn complaints on civic tech forums, including the Opendata.ch community, about broken links and mismatched metadata, both of which are symptoms of the underlying duplication problem. A consolidated archive, properly governed, should fix both. The city has set an internal deadline of December 31, 2026 to close the compliance gap.