Editing Basilica Cistern (section)

== Restoration history ==

=== 1985–1987 works ===
The first major modern restoration of the Basilica Cistern was undertaken by the Istanbul Metropolitan Municipality between 1985 and 1987.<ref name="Goksu2018" /> More than 50,000 tons of silt were removed from the reservoir, uncovering the Medusa-head column bases.<ref name="IBBMiras2022">{{cite report |title=Yerebatan Sarnıcı Müzesi: Daha Derine |publisher=İBB Miras / Istanbul Metropolitan Municipality |year=2022 |type=Exhibition brochure and restoration report }}</ref> Elevated wooden walkways were introduced, allowing the structure to open to the public as a museum in 1987.<ref name="Freely2004">{{cite book |last1=Freely |first1=John |last2=Çakmak |first2=Ahmet S. |title=Byzantine Monuments of Istanbul |publisher=Cambridge University Press |year=2004 }}</ref>

=== 2020–2022 restoration ===
A comprehensive restoration was carried out between 2020 and 2022 by the İBB Miras team.<ref name="IBBMiras2022" /> The deteriorated iron tie-rods were replaced with stainless-steel tension rods, anchored with star-shaped plates, to improve seismic resilience.<ref name="AydinGun2020">{{cite journal |last1=Aydın Gün |first1=Ş. |last2=Kurban |first2=Y. C. |last3=Yalçıner |first3=C. Ç. |last4=Büyüksaraç |first4=A. |last5=Gündoğdu |first5=E. |last6=Altunel |first6=E. |title=High-resolution ground penetrating radar investigation of Yerebatan (Basilica) Cistern in Istanbul (Constantinople) for restoration purposes |journal=Zenodo |year=2020 |doi=10.5281/zenodo.3930402 |url=https://doi.org/10.5281/zenodo.3930402 }}</ref>

Concrete walkways and a 50 cm-thick cement render added in the mid-20th century were dismantled. Approximately 1,440 m³ of concrete and 1,600 m³ of sediment were removed, revealing the original 6th-century Byzantine brick floor beneath.<ref name="IBBMiras2022" />

A new modular steel walkway was installed, physically separated from the historic structure, improving structural performance and visitor experience.<ref name="IBBMiras2022" /> Conservation treatments included gentle cleaning of marble and brick surfaces to remove biological growth and salt crystallization.<ref name="Goksu2018">{{cite journal |last1=Göksu |first1=G. |last2=Ergül |first2=M. |title=Restoration applications and material deterioration in historical cisterns: Basilica Cistern as a case study |journal=International Journal of Conservation Science |volume=9 |issue=3 |year=2018 |pages=409–420 |url=https://ijcs.ro/public/IJCS-18-36_Goksu.pdf }}</ref>

New LED lighting and sensors were also installed to support atmospheric lighting and non-invasive digital exhibitions.<ref name="IBBMiras2022" />