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

Istanbul's municipal archive has a sprawling, quietly embarrassing problem: tens of thousands of building files held across the Istanbul Metropolitan Municipality's digital infrastructure contain duplicate photographs — some structures logged under three or four separate image sets, others with no usable image at all. The issue, long treated as a bureaucratic footnote, is now drawing sharper scrutiny because those same records underpin the city's accelerating seismic risk survey program, launched formally after the February 2023 Kahramanmaraş earthquakes killed more than 50,000 people across southern Turkey.

The stakes are not abstract. Istanbul sits on or near the North Anatolian Fault, and urban planners have warned for years that a major quake beneath the Marmara Sea could cause catastrophic damage to the city's older residential stock. When field engineers try to cross-reference a building's structural assessment with its permit history, duplicate or misfiled images slow the verification process — sometimes by days. In a post-disaster triage scenario, that lag translates directly into risk.

A Fragmented System Built Layer by Layer

The duplication problem did not appear overnight. It accumulated across roughly fifteen years of incremental digitisation efforts, each carried out by a different directorate with its own file-naming conventions and storage protocols. The Istanbul Metropolitan Municipality's Department of Urban Transformation began its own scanning initiative around 2011, uploading permit photographs to one server. The separately administered district municipalities — Fatih, Beyoğlu, Kadıköy and the other 36 — maintained parallel databases. When Ankara mandated a unified national property registry push after 2018, the data migration pulled records from all those sources without a deduplication pass. The result was layered redundancy baked into the system's foundations.

Galata Tower's surrounding historic blocks in Beyoğlu offer a concrete illustration. Properties in the Kuledibi and Şişhane micro-neighbourhoods, many of them nineteenth-century apartment buildings undergoing mandatory seismic assessment under Turkey's Urban Transformation Law (Law No. 6306, enacted 2012), show up in the municipal archive with duplicate image sets dating from separate inspection rounds in 2015, 2019 and 2023. Field crews from ISMEP — the Istanbul Seismic Risk Mitigation and Emergency Preparedness Project, backed partly by World Bank financing — have flagged the overlap as a routine obstacle during building triage in the historic peninsula and inner districts.

What the Records Actually Show

Turkey's General Directorate of Land Registry and Cadastre, known by its Turkish acronym TKGM, publishes periodic data on the national property digitisation effort. As of its most recently available annual bulletin, the Istanbul registry alone contained records for more than 3.7 million parcels — a volume that makes manual deduplication impractical without automated tooling. The Istanbul Metropolitan Municipality allocated 47 million Turkish lira in its 2025 revised budget to information technology modernisation across its urban planning directorates, a line item that city council documents confirm includes database standardisation work, though progress has been uneven across departments.

The broader context is a city government operating under significant political and financial pressure. Mayor Ekrem İmamoğlu's administration has clashed repeatedly with central government ministries over access to funding streams and regulatory authority, particularly on urban transformation projects where national and municipal jurisdictions overlap. That friction has slowed coordinated data-sharing between the municipality and the Housing Development Administration of Turkey, known as TOKİ, which holds its own photographic archive for buildings it has constructed or approved for demolition across districts like Fikirtepe in Kadıköy and Başıbüyük in Maltepe.

For residents and property owners, the practical consequence is friction at the worst possible time. A homeowner in Balat or Çarşamba who submits documentation for a seismic retrofit subsidy may find their application stalled while administrators reconcile conflicting image records tied to the same address. The Istanbul Metropolitan Municipality's Urban Transformation hotline — reachable at 153 — has been advising applicants since early 2025 to submit their own timestamped photographs alongside official paperwork specifically to work around the archive inconsistencies. That workaround is functional, if inelegant. The longer-term fix requires a unified image registry with automatic hash-based deduplication, something IT procurement documents suggest the municipality is now formally tendering. A contract award is expected before the end of 2026.