How Istanbul's Building Stock Ended Up Drowning in Duplicate Images — and What's Being Done About It

Istanbul's municipal property database contains hundreds of thousands of building entries, and a growing share of them are backed by the same photograph appearing under multiple addresses. The Istanbul Metropolitan Municipality's digital cadastre unit, operating out of offices in Kagithane, confirmed earlier this year that a structured duplicate-image replacement programme is now underway — a quiet administrative fix with real consequences for earthquake preparedness, heritage protection, and urban development approvals across one of Europe's largest cities.

The problem did not emerge overnight. It is the accumulated result of at least three separate, poorly synchronised documentation drives stretching back to the mid-2000s, each conducted by different arms of municipal and national government, each uploading photographs into systems that did not talk to each other.

Three Waves of Documentation, One Tangled Archive

The first wave came after the 1999 Marmara earthquake, when national authorities pushed districts to photograph and categorise every residential building for structural risk assessments. Fatih, Beyoglu, and Kadikoy were among the districts most intensively surveyed. The second wave arrived in the early 2010s when the Urban Transformation Law — Law No. 6306, passed in May 2012 — mandated fresh inspections of buildings classified as being on risky land. Contractors hired by individual district municipalities photographed properties, but uploaded images to a central TKGM (General Directorate of Land Registry and Cadastre) portal without consistent file-naming conventions. A single building on, say, Istiklal Caddesi could end up represented by images from 2008, 2013, and 2019, all tagged to slightly different coordinate entries.

The third and heaviest wave followed the February 2023 Kahramanmaras earthquakes. Istanbul authorities, anticipating a major event on the North Anatolian Fault, launched an emergency re-survey of the city's roughly 1.5 million buildings. Volunteer architects working with the Istanbul branch of the Chamber of Architects, headquartered in Mete Caddesi in Beyoglu, joined municipal teams in the field. Speed was the priority. Deduplication was not. By the time the field work wound down in late 2024, internal audits found that in some older districts — Balat, Zeyrek, parts of Uskudar — as many as one in five building entries carried at least one photograph that also appeared, verbatim, in a separate record elsewhere in the database.

Why Duplicate Images Create Real Danger

This is not merely a cleanliness problem. Planning officers processing demolition permits or heritage exemptions in Sultanahmet use the photographic record as part of their evidentiary chain. If the image attached to a building shows the facade of a different structure entirely — perhaps a warehouse in Zeytinburnu that happened to share the same stock photograph — the legal basis for an approval or a refusal is compromised. Lawyers for property owners in several Sisli redevelopment cases raised exactly this issue before the Istanbul Administrative Court in 2025, arguing that visual misidentification had tainted the administrative record.

The Kagithane digital cadastre unit began its replacement programme in January 2026, working outward from the highest-risk earthquake zones first. The methodology involves cross-referencing GPS metadata embedded in image files against the map coordinates of the registered address, then flagging any photograph whose metadata places it more than 50 metres from its listed location. Flagged entries are queued for a physical re-shoot by contracted surveyors, with a target completion date of December 2027 for the districts inside the historic peninsula and the first-ring neighbourhoods beyond it.

For residents and property owners, the practical advice is straightforward: anyone currently applying for a building permit, an urban transformation exemption, or a heritage conservation status review should formally request sight of the photographic evidence attached to their cadastral entry at their district's tapu müdürlüğü — land registry office — before submitting paperwork. Catching a duplicate image at that stage, rather than after an administrative decision has been issued, can save months of appeals. The Sisli, Fatih, and Kadikoy tapu offices all accept such requests in person; processing typically takes five to seven working days under current staffing levels.