How Istanbul's Building Stock Ended Up Full of Duplicate Images — and Why Fixing It Now Matters

Istanbul's municipal property database contains tens of thousands of duplicate images — photographs that appear under multiple building records, assigned to wrong addresses, or simply copied across entries when original documentation was unavailable. The Istanbul Metropolitan Municipality's urban information directorate acknowledged the problem in internal reviews conducted through 2024 and 2025, and remediation work is now underway across several district registries, including those covering Fatih, Beyoğlu and Ümraniye.

The issue did not arrive overnight. It is the product of at least three overlapping documentation crises stretching back to the early 2000s, each of which added a new layer of inaccuracy on top of the last. Understanding that history is essential to grasping why cleanup efforts are complicated, expensive, and politically charged in a city where accurate building records feed directly into earthquake preparedness planning.

Three Waves of Bad Data

The first wave came during the rapid digitalisation push that followed the 1999 Marmara earthquake. Municipalities across the Marmara region were pressed to move paper building files into electronic systems quickly. Field teams photographing structures in districts like Bağcılar and Sultangazi often used shared image libraries when a specific building could not be photographed — due to access problems, poor weather, or simply insufficient staffing. A single exterior shot of a generic five-storey apartment block might end up attached to a dozen different cadastral records. Nobody considered this a serious problem at the time; the priority was getting something into the system.

The second wave came between roughly 2010 and 2017, during a period of aggressive urban transformation projects. Under Turkey's Urban Transformation Law — Law No. 6306, enacted in May 2012 — hundreds of buildings in risk zones were demolished and rebuilt. During that churn, image records for demolished structures were often not retired. Instead, photographs of replacement buildings were sometimes imported by copying the closest available image already in the system, which meant newly built structures inherited the photographic record of whatever had stood on a neighbouring plot.

The third and most recent wave traces to the aftermath of the February 2023 Kahramanmaraş earthquakes. Istanbul accelerated its own seismic risk assessments, generating enormous volumes of new field photography. Integration of that material into the existing database was rushed, and spot audits conducted by the Istanbul Earthquake Risk Mitigation and Emergency Management Directorate — known by its Turkish acronym AKOM — found duplication rates in some district datasets running above 30 percent of total image records.

Why the Reckoning Arrives in 2026

Two pressures converged this year. First, the Municipality's updated Istanbul Resilience Plan, which sets a 2027 deadline for completing a verified structural inventory of all buildings in the city's highest seismic-risk zones, requires clean image records as part of each building's digital twin file. Duplicate or misassigned photographs make it impossible to confirm that a risk assessment corresponds to the correct structure.

Second, the property valuation cycle. Turkish municipalities recalibrate declared property values — the figures used to calculate emlak vergisi, or real estate tax — every four years. The next recalibration cycle opens in 2027, and accurate photographic documentation underpins the classification of each structure by age, condition, and type. Errors in that classification translate directly into either under-collection or legally contestable assessments.

The remediation program now active in Fatih and Beyoğlu involves cross-referencing existing photographs against satellite imagery from 2024 and against address coordinates held in the national address registration system, MERNİS. Where a photograph cannot be confirmed as matching a specific plot, the record is flagged for a physical re-inspection. District teams operating out of offices on Divanyolu Caddesi in Fatih and Pürtelaş Sokak in Beyoğlu are working through flagged records neighbourhood by neighbourhood.

For residents and property owners, the practical implication is straightforward. If you receive a notification from your district municipality requesting access to photograph your building's exterior, this is the process behind it. Refusing access delays your building's record being cleared, which can affect permit applications, insurance filings, and — most critically — whether your structure appears correctly in the seismic risk registry before the 2027 assessment deadline. Cooperation is not legally mandatory under current regulations, but municipal officials have indicated that unverified records will be held in a suspended category that complicates routine transactions until inspection is completed.